The green high-yield and high-efficiency cultivation techniques of integrated management of water and fertilizer for maize under mulch drip irrigation are described from the aspects of high yield target of maize and i...The green high-yield and high-efficiency cultivation techniques of integrated management of water and fertilizer for maize under mulch drip irrigation are described from the aspects of high yield target of maize and its component factor indexes,pre-sowing preparation,sowing,post-sowing management,field management at the seedling stage,integrated management of water and fertilizer for target yield of maize,rational application of micro-fertilizer,comprehensive prevention and control of diseases and pests,timely harvest,etc.,in order to provide a reference for agricultural technicians,maize farmers and maize industry development in northern Xinjiang.展开更多
Improving the yield of maize grain per unit area is needed to meet the growing demand for it in China, where the availability of fertile land is very limited.Modified fertilization management and planting density are ...Improving the yield of maize grain per unit area is needed to meet the growing demand for it in China, where the availability of fertile land is very limited.Modified fertilization management and planting density are efficient methods for increasing crop yield.Field experiments were designed to investigate the influence of modified fertilization management and planting density on grain yield and nitrogen use efficiency of the popular maize variety Zhengdan 958, in four treatments including local farmer's practice(FP), high-yielding and high efficiency cultivation(HH), super high-yielding cultivation(SH), and the control(CK).Trials were conducted in three locations of the Huang-Huai-Hai Plain in northern China.Compared with FP, SH was clearly able to promote N absorption and dry matter accumulation in post-anthesis, and achieve high yield and N use efficiency by increasing planting density and postponing the supplementary application of fertilizers.However, with an increase in planting density, the demand of N increased along with grain yield.Due to the input of too much N fertilizer, the efficiency of N use in SH was low.Applying less total N, ameliorating cultivation and cropping management practices should be considered as priority strategies to augment production potential and finally achieve synchronization between high yield and high N efficiency in fertile soils.However, in situations where soil fertility is low, achieving high yield and high N use efficiency in maize will likely depend on increased planting density and appropriate application of supplementary fertilizers postpone to the grain-filling stage.展开更多
Soil fertility management (SFM) has important implications for sustaining agricultural development and food self-sufifciency. Better understanding the determinants of farmers’ SFM can be a great help to the adoptio...Soil fertility management (SFM) has important implications for sustaining agricultural development and food self-sufifciency. Better understanding the determinants of farmers’ SFM can be a great help to the adoption of effective SFM practices. Based on a dataset of 315 plots collected from a typical rice growing area of South China, this study applied statistical method and econometric models to examine the impacts of land characteristics on farmers’ SFM practices at plot scale. Main results showed that in general land characteristics affected SFM behaviors. Securer land tenure arrangements facilitated effective practices of SFM through more diversiifed and more soil-friendly cropping pattern choices. Plot size signiifcantly reduced the intensities of phosphorus and potassium fertilizer application. Given other factors, 1 ha increase in plot size might reduce 3.0 kg ha-1 P2O5 and 1.8 kg ha-1 K2O. Plots far from the homestead were paid less attention in terms of both chemical fertilizers and manure applications. Besides, plots with better quality were put more efforts on management by applying more nitrogen and manure, and by planting green manure crops. Signiifcant differences existed in SFM practices between the surveyed villages with different socio-economic conditions. The ifndings are expected to provide important references to the policy-making incentive for improving soil quality and crop productivity.展开更多
Assessing spatial variability and mapping of soil properties constitute important prerequisites for soil and crop management in agricultural areas. To explore the relationship between soil spatial variability and land...Assessing spatial variability and mapping of soil properties constitute important prerequisites for soil and crop management in agricultural areas. To explore the relationship between soil spatial variability and land management, 256 samples were randomly collected at two depths (surface layer 0–20 cm and subsurface layer 20–40 cm) under different land use types and soil parent materials in Yujiang County, Jiangxi Province, a red soil region of China. The pH, soil organic matter (SOM), total nitrogen (TN), cation exchange capacity (CEC), and base saturation (BS) of the soil samples were examined and mapped. The results indicated that soils in Yujiang were acidified, with an average pH of 4.87 (4.03–6.46) in the surface layer and 4.99 (4.03–6.24) in the subsurface layer. SOM and TN were significantly higher in the surface layer (27.6 and 1.50 g kg–1, respectively) than in the subsurface layer (12.1 and 0.70 g kg–1, respectively), while both CEC and BS were low (9.0 and 8.0 cmol kg–1, 29 and 38% for surface and subsurface layers, respectively). Paddy soil had higher pH (mean 4.99) than upland and forest soils, while soil derived from river alluvial deposits (RAD) had higher pH (mean 5.05) than the other three parent materials in both layers. Geostatistical analysis revealed that the best fit models were exponential for pH and TN, and spherical for BS in both layers, while spherical and Gaussian were the best fitted for SOM and CEC in the surface and subsurface layers. Spatial dependency varied from weak to strong for the different soil properties in both soil layers. The maps produced by selecting the best predictive variables showed that SOM, TN, and CEC had moderate levels in most parts of the study area. This study highlights the importance of site-specific agricultural management and suggests guidelines for appropriate land management decisions.展开更多
By analyzing and extracting the research progress on nitrogen fertilization in wheat, a dynamic knowledge model for management decision-making on total nitrogen rate, ratios of organic to inorganic and of basal to dre...By analyzing and extracting the research progress on nitrogen fertilization in wheat, a dynamic knowledge model for management decision-making on total nitrogen rate, ratios of organic to inorganic and of basal to dressing nitrogen under different environments and cultivars in wheat was developed with principle of nutrient balance and by integrating the quantitative effects of grain yield and quality targets, soil characters, variety traits and water management levels. Case studies on the nitrogen fertilization model with the data sets of different eco-sites, cultivars, soil fertility levels, grain yield and quality targets and water management levels indicate a good performance of the model system in decision-making and wide applicability.展开更多
To determine appropriate quantities of water and fertilizer required for early growth of hybrid poplar cuttings,we recorded the growth traits of four clones grown under four factors(irrigation and nitrogen,phosphorus,...To determine appropriate quantities of water and fertilizer required for early growth of hybrid poplar cuttings,we recorded the growth traits of four clones grown under four factors(irrigation and nitrogen,phosphorus,and potassium fertilizers),each with four levels,using an orthogonal experimental design.A logistic model was used to estimate growth in height.The growth curves for tree height were sigmoid,and the model R^2 values were greater than 0.9,which indicated that the fit was highly significant.ANOVA results for tree height and basal diameter indicated that all sources of variance showed significant differences(p<0.001).The average tree height and basal diameter for all the four clones under the different treatments ranged from 155.39 to 235.04 cm,and from 13.71 to 17.42 mm,respectively.A highly positive correlation between the extreme k value and tree height was observed,suggesting that the k value was an accurate estimation of tree height.For model parameters,the earliest average time point for the onset of the rapid growth period of poplar clones was 131 d,and the highest average increment in tree height during the rapid growth period was 138.78 cm.The highest average tree height for all clones under each factor was 219,210.51,200,and 201 cm when treated with either 1200 mL of water applied every third day,3 g of nitrogen,0 g of phosphorus,or 0 g of potassium,respectively.The most suitable treatment for the early growth of hybrid poplar cuttings,as suggested by the developed logistic model,was 1200 mL of water applied every third day and three applications of 1 g nitrogen(in the form of CH4N2O).展开更多
To achieve the purpose of reducing farm non-point source pollution, we integrated site specific nitrogen management precise irrigation, controlled drainage, and wetland eco-repair system in dike area of Taihu basin. D...To achieve the purpose of reducing farm non-point source pollution, we integrated site specific nitrogen management precise irrigation, controlled drainage, and wetland eco-repair system in dike area of Taihu basin. During investigation, it had given prominence for the water and fertilizer coupling effects of precise irrigation and site specific nutrient management, the characteristics of integration on controlled irrigation, controlled drainage and wetland ecosystem non-point source pollution control. Then the water and fertilizer integrated management mode of paddy field was put forward in Taihu basin where the water production efficiency increased to 1.64 kg. m-3, water saved 37.8%, fertilizer use efficiency raised 15,4%, yield raised 10%, and N, P load decreased 26%-72%. The modern agricultural and farmland ecosystems that control and cut down the farm non-point source pollution came into being, which can be a reference by Taihu basin to control its agricultural non-point source pollution and eutrophicated water body.展开更多
The amino acids and the volatile substances in grapes and wines play important roles in their quality,and the concentrations of these substances can be changed by how a vineyard is managed,e.g.,irrigation and fertigat...The amino acids and the volatile substances in grapes and wines play important roles in their quality,and the concentrations of these substances can be changed by how a vineyard is managed,e.g.,irrigation and fertigation regimes.This study aimed to evaluate the effect of fertilizer and water management on the distribution of amino acids,the volatile component profiles,and the sensory characteristics of Cabernet Sauvignon grapes and wines.The results showed that the amino acid concentration in grape berries was the highest under the 100%local fertilizer rate(HF)and 100%water irrigation quota(HW)treatment,and the volatile component concentration in wine was the highest under HF and 80%water irrigation quota(MW)treatment.The effect of irrigation on the amino acid content in grapes was greater than that of fertigation.The synergistic effect of fertilizer and water on arginine,serine,and glutamine in grape berries was significant.The interactive effect of fertigation and irrigation on the volatile substance in grapes was greater than that of fertigation and irrigation alone.The influence of irrigation on volatile substances in wines was greater than that of fertigation.In addition,there was also a correlation between the concentrations of multiple amino acids in grapes and volatile components in wines.Principal component analysis showed that the wine from the HFMW treatment had the best quality among all treatments.展开更多
The objective of this study was to determine the morphology mechanism of nitrogen (N) fertilizer rates and ratio on lodging resistance through analying its effects among lodging index (LI), lodging-related morphol...The objective of this study was to determine the morphology mechanism of nitrogen (N) fertilizer rates and ratio on lodging resistance through analying its effects among lodging index (LI), lodging-related morphological traits and physical strength in basal intemodes by comparing japonica and indica super rice cultivars. Field experiments, with three nitrogen levels (0, 150 and 300 kg ha-L) and two ratios of basal to topdressing (8:2 and 5:5) with two super rice cultivars (Yliangyou 2 and Wuyunjing 23), were conducted in the Baolin Farm, Danyang Country, Jiangsu Province, China, in 2011 and 2012. Effects of N fertilizer rates and ratios on morphology of whole plant, morphology traits in basal intemodes and culm's physical strength parameters were investigated at 20 d after full heading stage. LI of Yliangyou 2 was significant greater than that of Wuyunjing 23 due to larger bending moment by whole plant (WP) with higher plant height and gravity center height. With higher volume of N fertilizer, LI of two super rice cultivars was increased conspicuously. However, no significant effect was detected with increase of panicle fertilizer ratio. The size of breaking strength (M) in basal intemodes was the key factor determining LI among N fertilizer treatments. Correlation analysis revealed that M value was positively related bending stress (BS) of Wuyunjing 23 and section modulus (Z) of Yliangyou 2, respectively. The higher N fertilizer levels induced reduction ofBS of Wuyunjing 23 due to weak culm and leaf sheath plumpness status and reduced Z of Yliangyou 2 owning to small diameter and culm wall thickness, consequently, influencing their M indirectly. These results suggested that breaking strength was the key factor influencing LI with increase of N fertilizer levels. However, the lodging-related morphology mechanism was different with genotypes. Culm wall thickness and diameter in basal internodes of indica super rice and culm and leaf sheath plumpness status of japonica super rice influenced breaking strength, as well as lodging index, respectively.展开更多
We compared chemical and biological properties of soils in organically and conventionally fertilized apple orchards in Nagano Prefecture (one of the major apple producing regions in Japan). Five apple orchards with di...We compared chemical and biological properties of soils in organically and conventionally fertilized apple orchards in Nagano Prefecture (one of the major apple producing regions in Japan). Five apple orchards with different fertilizer management systems were used for this study. The total carbon and total nitrogen contents were higher in the organically fertilized orchard, while the total phosphorus and total potassium were at similar levels in both organically and conventionally fertilized orchards. The bacterial biomass did not differ between the two orchards, but the N circulation activity was clearly higher in the organically fertilized orchard from April to December. Total carbon from 50,000 to 60,000 mg/kg, total nitrogen at about 3000 to 4000 mg/kg, and a C/N ratio of 15 - 20 were suggested to be suitable conditions for a high level of apple production under an organic fertilizer management system.展开更多
Background: Forest fertilization offers a means to increase the production of renewable resources.Nitrogen is the most common fertilizer in boreal upland forests.There is plenty of research on the effect of nitrogen ...Background: Forest fertilization offers a means to increase the production of renewable resources.Nitrogen is the most common fertilizer in boreal upland forests.There is plenty of research on the effect of nitrogen fertilization on volume growth, but less research on the optimal timing of fertilization and optimal management of fertilized stands.Methods: This study used simulation and optimization to analyze the profitability of fertilization, optimal management of fertilized stands and the effects of fertilization on cash flows and timber yields.The management of 100 stands representing the most common growing sites of Scots pine and Norway spruce was optimized.Results: Fertilization improved profitability in most of the analyzed stands.Profitability improved most in spruce stands growing on mesic site.Improving stem quality increased the economic benefit of fertilization.The timber yields of medium-aged conifer stands can be increased by almost 1 m^3·ha^(-1)·a^(-1)(15%) in sub-xeric pine and mesic spruce sites and about 0.5 m^3·ha^(-1)·a^(-1)(5%) in mesic pine and herb-rich spruce sites when the recommended nitrogen dose(150kg·ha^(-1)) is applied once in 30 years.Conclusions: Nitrogen fertilization of boreal conifer forest should be used mainly in spruce-dominated stands growing on medium sites.The gains are the highest in stands where the mean tree diameter is 16–20 cm and stand basal area is 14–20 m^2·ha^(-1).展开更多
Nitrogen retention within a watershed reduces the amount of N exported to the ocean;however, it worsens environmental problems, including surface water eutrophication, aquifer pollution, acid rain, and soil acidificat...Nitrogen retention within a watershed reduces the amount of N exported to the ocean;however, it worsens environmental problems, including surface water eutrophication, aquifer pollution, acid rain, and soil acidification. Here, we adopted the Soil and Water Assessment Tool(SWAT) model to describe the riverine N output and retention effects in the Shanmei Reservoir Basin, a subtropical mountainous basin located in Quanzhou City, Southeast China. The results revealed that farmlands and orchards in the upstream and central parts of the basin were the dominant land use types, which contributed large N yields. Fertilizer application was the key source of riverine N output and N retention within the basin. On average, approximately 64% of anthropogenic N inputs were retained within the basin, whereas 36% of total N was exported to the downstream and coastal areas. The average N retention efficiency was 80% in a dry year, and within the year, N retention occurred in spring and summer and N release occurred in autumn and winter. The annual variation in N retention within the basin was largely dominated by changes in rainfall and runoff, whereas the seasonal characteristics of N retention were mainly affected by fertilization. Even with a large decrease in fertilizer application, owing to the contributions of the residual N pool and river background, the riverine N output still maintained a certain base value. The effects of precipitation, land use types, and agricultural fertilizer on N retention should be comprehensively considered to implement reasonable N management measures.展开更多
Taking annual Heracl'eum moellendorffii Hance as the material,this research studied the epidemic dynamics of H.moellendorffii Hance powdery mildew and plant growth by using the interactive methods of soil moisture...Taking annual Heracl'eum moellendorffii Hance as the material,this research studied the epidemic dynamics of H.moellendorffii Hance powdery mildew and plant growth by using the interactive methods of soil moisture and soil organic matter.The results showed that the interaction of higher soil moisture content(60%-80%)and soil organic matter content(75-100 g•kg^(-1))had few diseases,dosease index and area under disease progression curve(AUDPC)compared with those of other treatments,thus could effectivley control powdery mildew disease.Moreover,higher soil moisture and organic matter content increased the yield,contents of soluble sugar,soluble protein,vitamin C and coumarin in H.moellendorffii Hance.展开更多
Pennisetum giganteum z. x. lin selected by the National Juncao Center is a high-yielding and high-quality Juncao variety. It is a high-quality horticultural variety that grows upright, and has tall plants with high yi...Pennisetum giganteum z. x. lin selected by the National Juncao Center is a high-yielding and high-quality Juncao variety. It is a high-quality horticultural variety that grows upright, and has tall plants with high yield and high value. Planting should be carried out in the right time to ensure the quality of planting and promote the seedlings to be tidy and strong, and according to the row spacing of 80 cm, plant spacing of 40 cm, 2 plants per hole, about 2 000 holes per 667 m2, with the need for furrowing. At the seedling stage, the soil should be kept moist, and watered in time when it is dry and lacking water. P. giganteum is fertilizer-tolerant and sensitive to fertilizers, and requires a reasonable and economical amount of fertilizer.展开更多
Climate change is increasingly affecting farm-level decisions on when to plant and which climate smart agriculture (CSA) options to use. This study was conducted to determine the profitability and farmer acceptability...Climate change is increasingly affecting farm-level decisions on when to plant and which climate smart agriculture (CSA) options to use. This study was conducted to determine the profitability and farmer acceptability of different CSA options for maize-bean production in drought-prone areas of Uganda. It was conducted on-farm in Rakai and Nakasongola districts during 2020 and 2021. Variables included: planting date (early vs late);varieties (common beans: NABE 4 and NAROBEAN 2, and maize: Longe 5 and Bazooka);intercropping versus pure stand;and fertiliser use (manure, Diammonium phosphate (DAP) or combination). The experimental design was split-split plot, replicated six times. Over two years, early planting caused 16% and up to 46% higher yields of maize and beans, respectively, than late planting, resulting in 14% - 28% and 18% - 43% higher Benefit/Cost (B/C) ratio for maize and beans, respectively. Intercropping reduced maize and beans yield by 16% - 25% and 52% - 57%, respectively. The B/C was highest for sole maize;intercropping was more profitable than sole beans. Fertilizer (DAP) was most profitable when Bazooka was early-planted as sole crop followed by intercrop. For late planted-crop, manure was better. These practices were more beneficial when applied simultaneously for both crops excluding bean variety. Farmers’ lessons stressed the importance of early planting and fertilizer use;however, majority indicated they were to adopt more than two of the practices tested.展开更多
Investigating the impact of apple-dominated areas on nitrogen(N)and phosphorus(P)losses at a basin scale was essential for the sustainable development of apple industry in China.This study conducted a survey on fertil...Investigating the impact of apple-dominated areas on nitrogen(N)and phosphorus(P)losses at a basin scale was essential for the sustainable development of apple industry in China.This study conducted a survey on fertilizer application and built a Soil and Water Assessment Tool(SWAT)model to quantita-tively analyze the N and P losses in the Qixia apple-dominated area.Additionally,the decreases in N and P losses through adjusting the fertilizer application modes were evaluated.Results showed that average N and P losses in the Wulong River Basin(WRB)were 44.4 and 0.365 kg ha^(-1)in 2011-2017,respectively,and apple orchards accounted for 733%and 51.4%of the total N and P losses in the basin.Under nine fertilizer scheduling scenarios,three fertilizer schedule scenarios,automatic fertilizer application(S-AUTO),"one shot"mode(S1),and regulated fertilizer application(S-BSD),had the lowest N and P losses in apple orchards.The decreases in N loss ranged from 20.6%to 26.1%at the subbasin scale and 14.8%-30.7%at the basin outlet when applying the S-AUTO,S1,and S-BSD fertilizer application modes in Qixia apple orchards and all apple orchards in the WRB.The reductions in P loss varied from 22.0%to 46.1%at the subbasin scale and 14.6%-25.6%at the basin outlet.In orchard-dominated basin,N and P losses can be effectively reduced by optimizing the orchard fertilizer scheduling strategies.展开更多
The creation of controlled-release urea (CRU) is a potent substitute for conventional fertilizers in order to preserve the availability of nitrogen (N) in soil,prevent environmental pollution,and move toward green agr...The creation of controlled-release urea (CRU) is a potent substitute for conventional fertilizers in order to preserve the availability of nitrogen (N) in soil,prevent environmental pollution,and move toward green agriculture.The main objectives of this study were to assess the impacts of CRU’s full application on maize production and to clarify the connection between the nutrient release pattern of CRU and maize nutrient uptake.In order to learn more about the effects of CRU application on maize yields,N uptake,mineral N (N_(min)) dynamics,N balance in soil-crop systems,and economic returns,a series of field experiments were carried out in 2018–2020 in Dalian City,Liaoning Province,China.There were 4 different treatments in the experiments:no N fertilizer input (control,CK);application of common urea at 210 kg ha^(-1)(U),the ideal fertilization management level for the study site;application of polyurethane-coated urea at the same N input rate as U (PCU);and application of PCU at a 20% reduction in N input rate (0.8PCU).Our findings showed that using CRU (i.e.,PCU and 0.8 PCU) may considerably increase maize N absorption,maintain maize yields,and increase N use efficiency (NUE) compared to U.The grain yield showed considerable positive correlations with total N uptake in leaf in U and 0.8 PCU,but negative correlations with that in PCU,indicating that PCU caused excessive maize absorption while 0.8 PCU could achieve a better yield response to N supply.Besides,PCU was able to maintain N fertilizer in the soil profile 0–20 cm away from the fertilization point,and higher N_(min)content was observed in the 0–20 cm soil layer at various growth stages,particularly at the middle and late growing stages,optimizing the temporal and spatial distributions of N_(min).Additionally,compared to that in U,the apparent N loss rate in PCU was reduced by 36.2%,and applying CRU (PCU and 0.8 PCU) increased net profit by 8.5% to 15.2% with less labor and fertilization frequency.It was concluded that using CRU could be an effective N fertilizer management strategy to sustain maize production,improve NUE,and increase economic returns while minimizing environmental risks.展开更多
Hydrolysis of organic phosphorus(P) by soil phosphatases is an important process of P cycling in terrestrial ecosystems, significantly affected by nitrogen(N) and/or P fertilization. However, how soil acid phosphatase...Hydrolysis of organic phosphorus(P) by soil phosphatases is an important process of P cycling in terrestrial ecosystems, significantly affected by nitrogen(N) and/or P fertilization. However, how soil acid phosphatase(ACP) and alkaline phosphatase(ALP) activities respond to N and/or P fertilization and how these responses vary with climatic regions, ecosystem types, and fertilization management remain unclear. This knowledge gap hinders our ability to assess P cycling and availability from a global perspective. We performed a meta-analysis to evaluate the global patterns of soil ACP and ALP activities in response to N and/or P addition. We also examined how climatic regions(arctic to tropical), ecosystem types(cropland, grassland, and forest), and fertilization management(experiment duration and fertilizer type and application rate) affected changes in soil phosphatases after fertilization. It was shown that N fertilizer resulted in 10.1% ± 2.9% increase in soil ACP activity but a minimal effect on soil ALP activity. In contrast, P fertilizer resulted in 7.7% ± 2.6% decrease in soil ACP activity but a small increase in soil ALP activity. The responses of soil ACP and ALP activities to N and/or P fertilization were largely consistent across climatic regions but varied with ecosystem types and fertilization management, and the effects of ecosystem types and fertilization management were enzyme-dependent. Random forest analysis identified climate(mean annual precipitation and temperature) and change in soil pH as the key factors explaining variations in soil ACP and ALP activities. Therefore, N input and ecosystem types should be explicitly disentangled when assessing terrestrial P cycling.展开更多
Nitrogen fertilizer application has accelerated the agricultural soil N cycle while ensuring food security.Gaseous reactive N emissions from orchards,vegetables and tea plantations(OVT)are less understood than those f...Nitrogen fertilizer application has accelerated the agricultural soil N cycle while ensuring food security.Gaseous reactive N emissions from orchards,vegetables and tea plantations(OVT)are less understood than those from cereal crops.This paper presents a compilation of data on soil ammonia,nitrous oxide,and nitric oxide emissions from 1454 OVT systems at 184 unique experimental locations worldwide aiming to investigate their emission characteristics,emission factors(EF),and contribution to total farmland emissions.NH_(3)and N_(2)O emissions from orchards and N_(2)O and NO emissions from vegetable production were significantly higher in China than in the rest of the world,regardless of fertilizer application,while N_(2)O emissions from tea plantations were lower than for vegetables.The EF of NH_(3)for vegetables was close to the global mean value with urea application but significantly higher than that of orchards.The EF of N_(2)O in orchards and vegetables was comparable to the global median value,while in tea plantations,the value was 2.3 times higher than the global median value.Current estimates suggest that direct emissions of NH_(3),N_(2)O,and NO from OVT systems are equivalent to approximately a quarter,two thirds and a half of the total farmland in China,respectively.Future research needs to strengthen observational field studies in establishing standard sampling methods for gaseous N emissions and implementing knowledge-based management measures to help achieve the green development of agriculture.展开更多
The DeNitrification–DeComposition(DNDC)model is a process model with a series of carbon and nitrogen biogeochemistry in agro-ecosystems.It incorporates the driving factors of the ecological environment and aims to si...The DeNitrification–DeComposition(DNDC)model is a process model with a series of carbon and nitrogen biogeochemistry in agro-ecosystems.It incorporates the driving factors of the ecological environment and aims to simulate the carbon and nitrogen cycle in the terrestrial ecosystem.Furthermore,the model can be applied effectively in a paddy ecosystem.Based on an investigation and literature review,this study summarized and analyzed the impact of agricultural practices such aswatermanagement,fertilizer application,and strawincorporation on greenhouse gas emissions and soil carbon storage.After years of improvement,the DNDC model can presently be used effectively to evaluate the carbon sequestration and emissions mitigation potential of various agricultural practices.However,the related details of scientific processes of agricultural management,such as biochar incorporation and plastic mulching in paddy fields,should be added or modified and combined with experimental cases of actual agricultural practices to complete the calibration of the model,provide theoretical support for its promotion,and establish a reliable method of evaluating carbon sequestration and emissions mitigation in paddy fields.展开更多
文摘The green high-yield and high-efficiency cultivation techniques of integrated management of water and fertilizer for maize under mulch drip irrigation are described from the aspects of high yield target of maize and its component factor indexes,pre-sowing preparation,sowing,post-sowing management,field management at the seedling stage,integrated management of water and fertilizer for target yield of maize,rational application of micro-fertilizer,comprehensive prevention and control of diseases and pests,timely harvest,etc.,in order to provide a reference for agricultural technicians,maize farmers and maize industry development in northern Xinjiang.
基金supported by grants from the National Natural Science Foundation of China(31371576,31071358,31301274)the European Union’s Seventh Framework Programme(NUE-CROPS 222645)+1 种基金the National Key Technology Support Program of China(2011BAD16B14,2012BAD04B05-2)the Special Fund for Agro-Scientific Research in the Public Interest of China(HY12031100,HY1203096)
文摘Improving the yield of maize grain per unit area is needed to meet the growing demand for it in China, where the availability of fertile land is very limited.Modified fertilization management and planting density are efficient methods for increasing crop yield.Field experiments were designed to investigate the influence of modified fertilization management and planting density on grain yield and nitrogen use efficiency of the popular maize variety Zhengdan 958, in four treatments including local farmer's practice(FP), high-yielding and high efficiency cultivation(HH), super high-yielding cultivation(SH), and the control(CK).Trials were conducted in three locations of the Huang-Huai-Hai Plain in northern China.Compared with FP, SH was clearly able to promote N absorption and dry matter accumulation in post-anthesis, and achieve high yield and N use efficiency by increasing planting density and postponing the supplementary application of fertilizers.However, with an increase in planting density, the demand of N increased along with grain yield.Due to the input of too much N fertilizer, the efficiency of N use in SH was low.Applying less total N, ameliorating cultivation and cropping management practices should be considered as priority strategies to augment production potential and finally achieve synchronization between high yield and high N efficiency in fertile soils.However, in situations where soil fertility is low, achieving high yield and high N use efficiency in maize will likely depend on increased planting density and appropriate application of supplementary fertilizers postpone to the grain-filling stage.
基金partly funded by the National Natural Science Foundation of China (71273268)
文摘Soil fertility management (SFM) has important implications for sustaining agricultural development and food self-sufifciency. Better understanding the determinants of farmers’ SFM can be a great help to the adoption of effective SFM practices. Based on a dataset of 315 plots collected from a typical rice growing area of South China, this study applied statistical method and econometric models to examine the impacts of land characteristics on farmers’ SFM practices at plot scale. Main results showed that in general land characteristics affected SFM behaviors. Securer land tenure arrangements facilitated effective practices of SFM through more diversiifed and more soil-friendly cropping pattern choices. Plot size signiifcantly reduced the intensities of phosphorus and potassium fertilizer application. Given other factors, 1 ha increase in plot size might reduce 3.0 kg ha-1 P2O5 and 1.8 kg ha-1 K2O. Plots far from the homestead were paid less attention in terms of both chemical fertilizers and manure applications. Besides, plots with better quality were put more efforts on management by applying more nitrogen and manure, and by planting green manure crops. Signiifcant differences existed in SFM practices between the surveyed villages with different socio-economic conditions. The ifndings are expected to provide important references to the policy-making incentive for improving soil quality and crop productivity.
基金This study was supported by the National Natural Science Foundation of China(41620104006 and 41977104)the Central Public-interest Scientific Institution Basal Research Fund for Chinese Academy of Tropical Agricultural Sciences(1630062018005).We thank the staff from Yujiang Soil and Fertilizer Extension Station,Jiangxi,China for help with soil sampling.
文摘Assessing spatial variability and mapping of soil properties constitute important prerequisites for soil and crop management in agricultural areas. To explore the relationship between soil spatial variability and land management, 256 samples were randomly collected at two depths (surface layer 0–20 cm and subsurface layer 20–40 cm) under different land use types and soil parent materials in Yujiang County, Jiangxi Province, a red soil region of China. The pH, soil organic matter (SOM), total nitrogen (TN), cation exchange capacity (CEC), and base saturation (BS) of the soil samples were examined and mapped. The results indicated that soils in Yujiang were acidified, with an average pH of 4.87 (4.03–6.46) in the surface layer and 4.99 (4.03–6.24) in the subsurface layer. SOM and TN were significantly higher in the surface layer (27.6 and 1.50 g kg–1, respectively) than in the subsurface layer (12.1 and 0.70 g kg–1, respectively), while both CEC and BS were low (9.0 and 8.0 cmol kg–1, 29 and 38% for surface and subsurface layers, respectively). Paddy soil had higher pH (mean 4.99) than upland and forest soils, while soil derived from river alluvial deposits (RAD) had higher pH (mean 5.05) than the other three parent materials in both layers. Geostatistical analysis revealed that the best fit models were exponential for pH and TN, and spherical for BS in both layers, while spherical and Gaussian were the best fitted for SOM and CEC in the surface and subsurface layers. Spatial dependency varied from weak to strong for the different soil properties in both soil layers. The maps produced by selecting the best predictive variables showed that SOM, TN, and CEC had moderate levels in most parts of the study area. This study highlights the importance of site-specific agricultural management and suggests guidelines for appropriate land management decisions.
基金supported by the National Natural Science Foundation of China(30030090)National High Tech R&D Program(863 Program)of China(2001AA245041,2001AA115420).
文摘By analyzing and extracting the research progress on nitrogen fertilization in wheat, a dynamic knowledge model for management decision-making on total nitrogen rate, ratios of organic to inorganic and of basal to dressing nitrogen under different environments and cultivars in wheat was developed with principle of nutrient balance and by integrating the quantitative effects of grain yield and quality targets, soil characters, variety traits and water management levels. Case studies on the nitrogen fertilization model with the data sets of different eco-sites, cultivars, soil fertility levels, grain yield and quality targets and water management levels indicate a good performance of the model system in decision-making and wide applicability.
基金financially supported by the National Key Research and Development Program of China(Grant No.2016YFD0600404)the Fundamental Research Funds for the Central Universities(2572017DA02)
文摘To determine appropriate quantities of water and fertilizer required for early growth of hybrid poplar cuttings,we recorded the growth traits of four clones grown under four factors(irrigation and nitrogen,phosphorus,and potassium fertilizers),each with four levels,using an orthogonal experimental design.A logistic model was used to estimate growth in height.The growth curves for tree height were sigmoid,and the model R^2 values were greater than 0.9,which indicated that the fit was highly significant.ANOVA results for tree height and basal diameter indicated that all sources of variance showed significant differences(p<0.001).The average tree height and basal diameter for all the four clones under the different treatments ranged from 155.39 to 235.04 cm,and from 13.71 to 17.42 mm,respectively.A highly positive correlation between the extreme k value and tree height was observed,suggesting that the k value was an accurate estimation of tree height.For model parameters,the earliest average time point for the onset of the rapid growth period of poplar clones was 131 d,and the highest average increment in tree height during the rapid growth period was 138.78 cm.The highest average tree height for all clones under each factor was 219,210.51,200,and 201 cm when treated with either 1200 mL of water applied every third day,3 g of nitrogen,0 g of phosphorus,or 0 g of potassium,respectively.The most suitable treatment for the early growth of hybrid poplar cuttings,as suggested by the developed logistic model,was 1200 mL of water applied every third day and three applications of 1 g nitrogen(in the form of CH4N2O).
基金Supported by NSFC (50839002)Society Development Program of Jiangsu Province (BS2007139)
文摘To achieve the purpose of reducing farm non-point source pollution, we integrated site specific nitrogen management precise irrigation, controlled drainage, and wetland eco-repair system in dike area of Taihu basin. During investigation, it had given prominence for the water and fertilizer coupling effects of precise irrigation and site specific nutrient management, the characteristics of integration on controlled irrigation, controlled drainage and wetland ecosystem non-point source pollution control. Then the water and fertilizer integrated management mode of paddy field was put forward in Taihu basin where the water production efficiency increased to 1.64 kg. m-3, water saved 37.8%, fertilizer use efficiency raised 15,4%, yield raised 10%, and N, P load decreased 26%-72%. The modern agricultural and farmland ecosystems that control and cut down the farm non-point source pollution came into being, which can be a reference by Taihu basin to control its agricultural non-point source pollution and eutrophicated water body.
基金the S&T Program of Hebei,China(Grant No.20327001D)the leading Talent Project of Science and Technology Innovation in Ningxia Hui Autonomous Region(Grant No.2022GKLRLX07).
文摘The amino acids and the volatile substances in grapes and wines play important roles in their quality,and the concentrations of these substances can be changed by how a vineyard is managed,e.g.,irrigation and fertigation regimes.This study aimed to evaluate the effect of fertilizer and water management on the distribution of amino acids,the volatile component profiles,and the sensory characteristics of Cabernet Sauvignon grapes and wines.The results showed that the amino acid concentration in grape berries was the highest under the 100%local fertilizer rate(HF)and 100%water irrigation quota(HW)treatment,and the volatile component concentration in wine was the highest under HF and 80%water irrigation quota(MW)treatment.The effect of irrigation on the amino acid content in grapes was greater than that of fertigation.The synergistic effect of fertilizer and water on arginine,serine,and glutamine in grape berries was significant.The interactive effect of fertigation and irrigation on the volatile substance in grapes was greater than that of fertigation and irrigation alone.The influence of irrigation on volatile substances in wines was greater than that of fertigation.In addition,there was also a correlation between the concentrations of multiple amino acids in grapes and volatile components in wines.Principal component analysis showed that the wine from the HFMW treatment had the best quality among all treatments.
基金supported by the Key Technologies R&D Program of China during the 12th Five-Year Plan period(2011BAD16B14,2012BAD20B05)the Agricultural Science and Technology Independent Innovation Funds of Jiangsu Province,China(CX(11)2011)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)
文摘The objective of this study was to determine the morphology mechanism of nitrogen (N) fertilizer rates and ratio on lodging resistance through analying its effects among lodging index (LI), lodging-related morphological traits and physical strength in basal intemodes by comparing japonica and indica super rice cultivars. Field experiments, with three nitrogen levels (0, 150 and 300 kg ha-L) and two ratios of basal to topdressing (8:2 and 5:5) with two super rice cultivars (Yliangyou 2 and Wuyunjing 23), were conducted in the Baolin Farm, Danyang Country, Jiangsu Province, China, in 2011 and 2012. Effects of N fertilizer rates and ratios on morphology of whole plant, morphology traits in basal intemodes and culm's physical strength parameters were investigated at 20 d after full heading stage. LI of Yliangyou 2 was significant greater than that of Wuyunjing 23 due to larger bending moment by whole plant (WP) with higher plant height and gravity center height. With higher volume of N fertilizer, LI of two super rice cultivars was increased conspicuously. However, no significant effect was detected with increase of panicle fertilizer ratio. The size of breaking strength (M) in basal intemodes was the key factor determining LI among N fertilizer treatments. Correlation analysis revealed that M value was positively related bending stress (BS) of Wuyunjing 23 and section modulus (Z) of Yliangyou 2, respectively. The higher N fertilizer levels induced reduction ofBS of Wuyunjing 23 due to weak culm and leaf sheath plumpness status and reduced Z of Yliangyou 2 owning to small diameter and culm wall thickness, consequently, influencing their M indirectly. These results suggested that breaking strength was the key factor influencing LI with increase of N fertilizer levels. However, the lodging-related morphology mechanism was different with genotypes. Culm wall thickness and diameter in basal internodes of indica super rice and culm and leaf sheath plumpness status of japonica super rice influenced breaking strength, as well as lodging index, respectively.
文摘We compared chemical and biological properties of soils in organically and conventionally fertilized apple orchards in Nagano Prefecture (one of the major apple producing regions in Japan). Five apple orchards with different fertilizer management systems were used for this study. The total carbon and total nitrogen contents were higher in the organically fertilized orchard, while the total phosphorus and total potassium were at similar levels in both organically and conventionally fertilized orchards. The bacterial biomass did not differ between the two orchards, but the N circulation activity was clearly higher in the organically fertilized orchard from April to December. Total carbon from 50,000 to 60,000 mg/kg, total nitrogen at about 3000 to 4000 mg/kg, and a C/N ratio of 15 - 20 were suggested to be suitable conditions for a high level of apple production under an organic fertilizer management system.
文摘Background: Forest fertilization offers a means to increase the production of renewable resources.Nitrogen is the most common fertilizer in boreal upland forests.There is plenty of research on the effect of nitrogen fertilization on volume growth, but less research on the optimal timing of fertilization and optimal management of fertilized stands.Methods: This study used simulation and optimization to analyze the profitability of fertilization, optimal management of fertilized stands and the effects of fertilization on cash flows and timber yields.The management of 100 stands representing the most common growing sites of Scots pine and Norway spruce was optimized.Results: Fertilization improved profitability in most of the analyzed stands.Profitability improved most in spruce stands growing on mesic site.Improving stem quality increased the economic benefit of fertilization.The timber yields of medium-aged conifer stands can be increased by almost 1 m^3·ha^(-1)·a^(-1)(15%) in sub-xeric pine and mesic spruce sites and about 0.5 m^3·ha^(-1)·a^(-1)(5%) in mesic pine and herb-rich spruce sites when the recommended nitrogen dose(150kg·ha^(-1)) is applied once in 30 years.Conclusions: Nitrogen fertilization of boreal conifer forest should be used mainly in spruce-dominated stands growing on medium sites.The gains are the highest in stands where the mean tree diameter is 16–20 cm and stand basal area is 14–20 m^2·ha^(-1).
基金funded by the National Key Research and Development Program of China (2018YFE0206400)the National Natural Science Foundations of China (41601535 and 41807159)。
文摘Nitrogen retention within a watershed reduces the amount of N exported to the ocean;however, it worsens environmental problems, including surface water eutrophication, aquifer pollution, acid rain, and soil acidification. Here, we adopted the Soil and Water Assessment Tool(SWAT) model to describe the riverine N output and retention effects in the Shanmei Reservoir Basin, a subtropical mountainous basin located in Quanzhou City, Southeast China. The results revealed that farmlands and orchards in the upstream and central parts of the basin were the dominant land use types, which contributed large N yields. Fertilizer application was the key source of riverine N output and N retention within the basin. On average, approximately 64% of anthropogenic N inputs were retained within the basin, whereas 36% of total N was exported to the downstream and coastal areas. The average N retention efficiency was 80% in a dry year, and within the year, N retention occurred in spring and summer and N release occurred in autumn and winter. The annual variation in N retention within the basin was largely dominated by changes in rainfall and runoff, whereas the seasonal characteristics of N retention were mainly affected by fertilization. Even with a large decrease in fertilizer application, owing to the contributions of the residual N pool and river background, the riverine N output still maintained a certain base value. The effects of precipitation, land use types, and agricultural fertilizer on N retention should be comprehensively considered to implement reasonable N management measures.
基金Supported by the National Key Research and Development Program of China(2016YFC0500307-06)。
文摘Taking annual Heracl'eum moellendorffii Hance as the material,this research studied the epidemic dynamics of H.moellendorffii Hance powdery mildew and plant growth by using the interactive methods of soil moisture and soil organic matter.The results showed that the interaction of higher soil moisture content(60%-80%)and soil organic matter content(75-100 g•kg^(-1))had few diseases,dosease index and area under disease progression curve(AUDPC)compared with those of other treatments,thus could effectivley control powdery mildew disease.Moreover,higher soil moisture and organic matter content increased the yield,contents of soluble sugar,soluble protein,vitamin C and coumarin in H.moellendorffii Hance.
文摘Pennisetum giganteum z. x. lin selected by the National Juncao Center is a high-yielding and high-quality Juncao variety. It is a high-quality horticultural variety that grows upright, and has tall plants with high yield and high value. Planting should be carried out in the right time to ensure the quality of planting and promote the seedlings to be tidy and strong, and according to the row spacing of 80 cm, plant spacing of 40 cm, 2 plants per hole, about 2 000 holes per 667 m2, with the need for furrowing. At the seedling stage, the soil should be kept moist, and watered in time when it is dry and lacking water. P. giganteum is fertilizer-tolerant and sensitive to fertilizers, and requires a reasonable and economical amount of fertilizer.
文摘Climate change is increasingly affecting farm-level decisions on when to plant and which climate smart agriculture (CSA) options to use. This study was conducted to determine the profitability and farmer acceptability of different CSA options for maize-bean production in drought-prone areas of Uganda. It was conducted on-farm in Rakai and Nakasongola districts during 2020 and 2021. Variables included: planting date (early vs late);varieties (common beans: NABE 4 and NAROBEAN 2, and maize: Longe 5 and Bazooka);intercropping versus pure stand;and fertiliser use (manure, Diammonium phosphate (DAP) or combination). The experimental design was split-split plot, replicated six times. Over two years, early planting caused 16% and up to 46% higher yields of maize and beans, respectively, than late planting, resulting in 14% - 28% and 18% - 43% higher Benefit/Cost (B/C) ratio for maize and beans, respectively. Intercropping reduced maize and beans yield by 16% - 25% and 52% - 57%, respectively. The B/C was highest for sole maize;intercropping was more profitable than sole beans. Fertilizer (DAP) was most profitable when Bazooka was early-planted as sole crop followed by intercrop. For late planted-crop, manure was better. These practices were more beneficial when applied simultaneously for both crops excluding bean variety. Farmers’ lessons stressed the importance of early planting and fertilizer use;however, majority indicated they were to adopt more than two of the practices tested.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFD0201202,No.2016YFD030080101,No.2022YFD1500701)supported by the Chinese Universities Scientific Fund under award numbers 1191-15051002,1191-10092004,and 1191-31051204.
文摘Investigating the impact of apple-dominated areas on nitrogen(N)and phosphorus(P)losses at a basin scale was essential for the sustainable development of apple industry in China.This study conducted a survey on fertilizer application and built a Soil and Water Assessment Tool(SWAT)model to quantita-tively analyze the N and P losses in the Qixia apple-dominated area.Additionally,the decreases in N and P losses through adjusting the fertilizer application modes were evaluated.Results showed that average N and P losses in the Wulong River Basin(WRB)were 44.4 and 0.365 kg ha^(-1)in 2011-2017,respectively,and apple orchards accounted for 733%and 51.4%of the total N and P losses in the basin.Under nine fertilizer scheduling scenarios,three fertilizer schedule scenarios,automatic fertilizer application(S-AUTO),"one shot"mode(S1),and regulated fertilizer application(S-BSD),had the lowest N and P losses in apple orchards.The decreases in N loss ranged from 20.6%to 26.1%at the subbasin scale and 14.8%-30.7%at the basin outlet when applying the S-AUTO,S1,and S-BSD fertilizer application modes in Qixia apple orchards and all apple orchards in the WRB.The reductions in P loss varied from 22.0%to 46.1%at the subbasin scale and 14.6%-25.6%at the basin outlet.In orchard-dominated basin,N and P losses can be effectively reduced by optimizing the orchard fertilizer scheduling strategies.
基金supported by the National Key R&D Program of China(No.2022YFD1700605)the National Natural Science Foundation of China(Nos.31872177 and31972511)the Fundamental Research Funds for Central Non-profit Scientific Institution,China(No.1610132-023005)。
文摘The creation of controlled-release urea (CRU) is a potent substitute for conventional fertilizers in order to preserve the availability of nitrogen (N) in soil,prevent environmental pollution,and move toward green agriculture.The main objectives of this study were to assess the impacts of CRU’s full application on maize production and to clarify the connection between the nutrient release pattern of CRU and maize nutrient uptake.In order to learn more about the effects of CRU application on maize yields,N uptake,mineral N (N_(min)) dynamics,N balance in soil-crop systems,and economic returns,a series of field experiments were carried out in 2018–2020 in Dalian City,Liaoning Province,China.There were 4 different treatments in the experiments:no N fertilizer input (control,CK);application of common urea at 210 kg ha^(-1)(U),the ideal fertilization management level for the study site;application of polyurethane-coated urea at the same N input rate as U (PCU);and application of PCU at a 20% reduction in N input rate (0.8PCU).Our findings showed that using CRU (i.e.,PCU and 0.8 PCU) may considerably increase maize N absorption,maintain maize yields,and increase N use efficiency (NUE) compared to U.The grain yield showed considerable positive correlations with total N uptake in leaf in U and 0.8 PCU,but negative correlations with that in PCU,indicating that PCU caused excessive maize absorption while 0.8 PCU could achieve a better yield response to N supply.Besides,PCU was able to maintain N fertilizer in the soil profile 0–20 cm away from the fertilization point,and higher N_(min)content was observed in the 0–20 cm soil layer at various growth stages,particularly at the middle and late growing stages,optimizing the temporal and spatial distributions of N_(min).Additionally,compared to that in U,the apparent N loss rate in PCU was reduced by 36.2%,and applying CRU (PCU and 0.8 PCU) increased net profit by 8.5% to 15.2% with less labor and fertilization frequency.It was concluded that using CRU could be an effective N fertilizer management strategy to sustain maize production,improve NUE,and increase economic returns while minimizing environmental risks.
基金financial support from the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDA23070202 and XDB40020000)the National Natural Science Foundation of China(Nos.41977068 and 41977105)the Programs of Chinese Academy of Sciences(No.QYZDB-SSW-DQC039)。
文摘Hydrolysis of organic phosphorus(P) by soil phosphatases is an important process of P cycling in terrestrial ecosystems, significantly affected by nitrogen(N) and/or P fertilization. However, how soil acid phosphatase(ACP) and alkaline phosphatase(ALP) activities respond to N and/or P fertilization and how these responses vary with climatic regions, ecosystem types, and fertilization management remain unclear. This knowledge gap hinders our ability to assess P cycling and availability from a global perspective. We performed a meta-analysis to evaluate the global patterns of soil ACP and ALP activities in response to N and/or P addition. We also examined how climatic regions(arctic to tropical), ecosystem types(cropland, grassland, and forest), and fertilization management(experiment duration and fertilizer type and application rate) affected changes in soil phosphatases after fertilization. It was shown that N fertilizer resulted in 10.1% ± 2.9% increase in soil ACP activity but a minimal effect on soil ALP activity. In contrast, P fertilizer resulted in 7.7% ± 2.6% decrease in soil ACP activity but a small increase in soil ALP activity. The responses of soil ACP and ALP activities to N and/or P fertilization were largely consistent across climatic regions but varied with ecosystem types and fertilization management, and the effects of ecosystem types and fertilization management were enzyme-dependent. Random forest analysis identified climate(mean annual precipitation and temperature) and change in soil pH as the key factors explaining variations in soil ACP and ALP activities. Therefore, N input and ecosystem types should be explicitly disentangled when assessing terrestrial P cycling.
基金financially supported by the Jiangsu Provincial Special Project for Carbon Peak Carbon Neutrality Science and Technology Innovation(BE2022423,BE2022308)the National Natural Science Foundation of China(42177285,42007072)the Startup Foundation for Introducing Talent of Nanjing Agricultural University(030/804028)。
文摘Nitrogen fertilizer application has accelerated the agricultural soil N cycle while ensuring food security.Gaseous reactive N emissions from orchards,vegetables and tea plantations(OVT)are less understood than those from cereal crops.This paper presents a compilation of data on soil ammonia,nitrous oxide,and nitric oxide emissions from 1454 OVT systems at 184 unique experimental locations worldwide aiming to investigate their emission characteristics,emission factors(EF),and contribution to total farmland emissions.NH_(3)and N_(2)O emissions from orchards and N_(2)O and NO emissions from vegetable production were significantly higher in China than in the rest of the world,regardless of fertilizer application,while N_(2)O emissions from tea plantations were lower than for vegetables.The EF of NH_(3)for vegetables was close to the global mean value with urea application but significantly higher than that of orchards.The EF of N_(2)O in orchards and vegetables was comparable to the global median value,while in tea plantations,the value was 2.3 times higher than the global median value.Current estimates suggest that direct emissions of NH_(3),N_(2)O,and NO from OVT systems are equivalent to approximately a quarter,two thirds and a half of the total farmland in China,respectively.Future research needs to strengthen observational field studies in establishing standard sampling methods for gaseous N emissions and implementing knowledge-based management measures to help achieve the green development of agriculture.
基金This study was financed by the National Key Research and Development Program of China,China(2017YFD0800204)Shanghai Agriculture Applied Technology Development Program,China(G2016060301 and 2018(1-3)).
文摘The DeNitrification–DeComposition(DNDC)model is a process model with a series of carbon and nitrogen biogeochemistry in agro-ecosystems.It incorporates the driving factors of the ecological environment and aims to simulate the carbon and nitrogen cycle in the terrestrial ecosystem.Furthermore,the model can be applied effectively in a paddy ecosystem.Based on an investigation and literature review,this study summarized and analyzed the impact of agricultural practices such aswatermanagement,fertilizer application,and strawincorporation on greenhouse gas emissions and soil carbon storage.After years of improvement,the DNDC model can presently be used effectively to evaluate the carbon sequestration and emissions mitigation potential of various agricultural practices.However,the related details of scientific processes of agricultural management,such as biochar incorporation and plastic mulching in paddy fields,should be added or modified and combined with experimental cases of actual agricultural practices to complete the calibration of the model,provide theoretical support for its promotion,and establish a reliable method of evaluating carbon sequestration and emissions mitigation in paddy fields.