Manure substitution improves maize yield by promoting soil fertility and mediating the microbial community in lime concretion black soil

Synthetic nitrogen(N)fertilizer has made a great contribution to the improvement of soil fertility and productivity,but excessive application of synthetic N fertilizer may cause agroecosystem risks,such as soil acidification,groundwater contamination and biodiversity reduction.Meanwhile,organic substitution has received increasing attention for its ecologically and environmentally friendly and productivity benefits.However,the linkages between manure substitution,crop yield and the underlying microbial mechanisms remain uncertain.To bridge this gap,a three-year field experiment was conducted with five fertilization regimes:i)Control,non-fertilization;CF,conventional synthetic fertilizer application;CF_(1/2)M_(1/2),1/2 N input via synthetic fertilizer and 1/2 N input via manure;CF_(1/4)M_(3/4),1/4 N input synthetic fertilizer and 3/4 N input via manure;M,manure application.All fertilization treatments were designed to have equal N input.Our results showed that all manure substituted treatments achieved high soil fertility indexes(SFI)and productivities by increasing the soil organic carbon(SOC),total N(TN)and available phosphorus(AP)concentrations,and by altering the bacterial community diversity and composition compared with CF.SOC,AP,and the soil C:N ratio were mainly responsible for microbial community variations.The co-occurrence network revealed that SOC and AP had strong positive associations with Rhodospirillales and Burkholderiales,while TN and C:N ratio had positive and negative associations with Micromonosporaceae,respectively.These specific taxa are implicated in soil macroelement turnover.Random Forest analysis predicted that both biotic(bacterial composition and Micromonosporaceae)and abiotic(AP,SOC,SFI,and TN)factors had significant effects on crop yield.The present work strengthens our understanding of the effects of manure substitution on crop yield and provides theoretical support for optimizing fertilization strategies.

Hole fertilization in the root zone facilitates maize yield and nitrogen utilization by mitigating potential N loss and improving mineral N accumulation

Reducing environmental impacts and improving N utilization are critical to ensuring food security in China.Although root-zone fertilization has been considered an effective strategy to improve nitrogen use efficiency (NUE),the effect of controlled-release urea (CRU) applied in conjunction with normal urea in this mode is unclear.Therefore,a 3-year field experiment was conducted using a no-N-added as a control and two fertilization modes (FF,furrow fertilization by manual trenching,i.e.,farmer fertilizer practice;HF:root-zone hole fertilization by point broadcast manually) at 210 kg N ha^(–1) (controlled-release:normal fertilizer=5:5),along with a 1-year in-situ microplot experiment.Maize yield,NUE and N loss were investigated under different fertilization modes.The results showed that compared with FF,HF improved the average yield and N recovery efficiency by 8.5 and 22.3%over three years,respectively.HF had a greater potential for application than FF treatment,which led to increases in dry matter accumulation,total N uptake,SPAD value and LAI.In addition,HF remarkably enhanced the accumulation of ^(15)N derived from fertilizer by 17.2%compared with FF,which in turn reduced the potential loss of^(15)N by 43.8%.HF increased the accumulation of N in the tillage layer of soils at harvest for potential use in the subsequent season relative to FF.Hence,HF could match the N requirement of summer maize,sustain yield,improve NUE and reduce environmental N loss simultaneously.Overall,root-zone hole fertilization with blended CRU and normal urea can represent an effective and promising practice to achieve environmental integrity and food security on the North China Plain,which deserves further application and investigation.

Extreme Climatic Characteristics and Their Effects on Maize Yield in Hei-longjiang Province from 1961 to 2020

This paper analyzed the extreme climatic characteristics of maize in Heilongjiang Province during different growth periods using the climate data and maize yield data from 1961 to 2020,and applied the principal component analysis to analyze the extent of different extreme climatic events affecting maize yield.The results showed that the extreme cold events showed a decreasing trend,and the extreme warm events showed an increasing trend,and the trend of extreme precipitation change was not obvious.Maize yield was negatively correlated with TN10p(cold nights),TX10p(warm days)and T8(days below the lower temperature limit),and positively correlated with TN90p(warm nights).T34(days above the upper temperature limit)and TX90p(warm days)during the tasseling-milking period were negatively correlated with the maize yield,and this part was concentrated in the southern part of Heilongjiang Province.The maize yield was positively correlated with the extreme precipitation during the seedling period and negatively correlated with the extreme precipitation during the filling-maturity period of maize,but the correlations were not significant.The effects of extreme weather events on maize yield were higher during the seedling and the filling-maturity periods than those during the jointing-tasseling and the tasseling-milking periods.The effects of extreme precipitation on the maize yield were less than those of the extreme temperature during different growth periods in all regions,but the effects of the extreme precipitation on maize yield were significantly higher in the Songnen Plain than those in other regions.There were regional differences in the impact of climate extremes on maize during different growth periods.The area with the greater impact of climate extremes during the seedling period was the Songnen Plain,the areas with the greater impact of climate extremes during the jointing-tasseling period were the northern part of the Sanjiang Plain,and the areas with the greater impact of climate extremes during the filling-maturity period were the Lesser Khingan Mountains and the semi-mountainous areas of Mudanjiang.

Impact of climate change on maize yield in China from 1979 to 2016

Climate change severely impacts agricultural production, which jeopardizes food security. China is the second largest maize producer in the world and also the largest consumer of maize. Analyzing the impact of climate change on maize yields can provide effective guidance to national and international economics and politics. Panel models are unable to determine the group-wise heteroscedasticity, cross-sectional correlation and autocorrelation of datasets, therefore we adopted the feasible generalized least square(FGLS) model to evaluate the impact of climate change on maize yields in China from 1979–2016 and got the following results:(1) During the 1979–2016 period, increases in temperature negatively impacted the maize yield of China. For every 1℃ increase in temperature, the maize yield was reduced by 5.19 kg 667 m^–2(1.7%). Precipitation increased only marginally during this time, and therefore its impact on the maize yield was negligible. For every 1 mm increase in precipitation, the maize yield increased by an insignificant amount of 0.043 kg 667 m^–2(0.014%).(2) The impacts of climate change on maize yield differ spatially, with more significant impacts experienced in southern China. In this region, a 1℃ increase in temperature resulted in a 7.49 kg 667 m^–2 decrease in the maize yield, while the impact of temperature on the maize yield in northern China was insignificant. For every 1 mm increase in precipitation, the maize yield increased by 0.013 kg 667 m^–2 in southern China and 0.066 kg 667 m^–2 in northern China.(3) The resilience of the maize crop to climate change is strong. The marginal effect of temperature in both southern and northern China during the 1990–2016 period was smaller than that for the 1979–2016 period.

Combined Application of Organic and Inorganic Fertilizers on Black Soil Fertility and Maize Yield

By two years (2007-2008) located fertilizer experiment, the effect of long-term combined application of organic and inorganic fertilizers on black soil fertility and crop yield was investigated in Shuangcheng City, Heilongjiang Province. The results showed that the combined application of organic and inorganic fertilizers could increase the organinc matter, alkaline nitrogen, available phosphorus and available potassium. At the same time, the increasing application of organic fertilizer could reduce the soil bulk density and improve the field moisture capacity. Field moisture capacity and organic matter of the combined application of high quantities of organic manure and inorganic fertilizers A1B5 treatment increased the fastest, organic matter increased by 3.33 g · kg-1 and field moisture capacity increased by 11.25% than the beginning of the experiment. Under the same fertilization, the combined application of organic and inorganic fertilizers' increasing production range was higher than the single chemical fertilizers' which was from 0.8% to 9.4%. The results showed that the combined application of organic and inorganic fertilizers could increase the nutrient contents of soil and also was the highest productivity contribution to black soil fertility. It was the best fertilization structure of increasing productivity level and improving the soil fertility.

Remote Sensing and GIS Based Spectro-Agrometeorological Maize Yield Forecast Model for South Tigray Zone, Ethiopia

Remote-sensing data acquired by satellite imageries have a wide scope in agricultural applications owing to their synoptic and repetitive coverage. This study reports the development of an operational spectro-agrometereological yield model for maize crop derived from time series data of SPOT VEGETATION, actual and potential evapotranspiration and rainfall estimate satellite data for the years 2003-2012. Indices of these input data were utilized to validate their strength in explaining grain yield recorded by the Central Statistical Agency through correlation analyses. Crop masking at crop land area was applied and refined using agro-ecological zones suitable for maize. Rainfall estimates and average Normalized Difference Vegetation Index were found highly correlated to maize yield with the former accounting for 85% variation and the latter 80%, respectively. The developed spectro-agrometeorological yield model was successfully validated against the predicted Zone level yields estimated by Central Statistical Agency (r2 = 0.88, RMSE = 1.405 q·ha-1 and 21% coefficient of variation). Thus, remote sensing and geographical information system based maize yield forecast improved quality and timelines of the data besides distinguishing yield production levels/areas and making intervention very easy for the decision makers thereby proving the clear potential of spectro-agrometeorological factors for maize yield forecasting, particularly for Ethiopia.

Optimized nitrogen application for maximizing yield and minimizing nitrogen loss in film mulching spring maize production on the Loess Plateau,China

Excessive use of N fertilizers(driven by high-yield goals)and its consequent environmental problems are becoming increasingly acute in agricultural systems.A 2-year field experiment was conducted to investigate the effects of three N application methods(application of solid granular urea once(OF)or twice(TF),application of solid granular urea mixed with controlled-release urea once(MF),and six N rates(0,60,120,180,240,and 300 kg N ha^(-1))on maize yield,economic benefits,N use efficiency,and soil N balance in the maize(Zea mays L.)film mulching system on the Loess Plateau,China.The grain yield and economic return of maize were significantly affected by the N rate and application method.Compared with the OF treatment,the MF treatment not only increased the maize yield(increased by 9.0-16.7%)but also improved the economic return(increased by 10.9-25.8%).The agronomic N use efficiency(NAE),N partial factor productivity(NPFP)and recovery N efficiency(NRE)were significantly improved by 19.3-66.7,9.0-16.7 and 40.2-71.5%,respectively,compared with the OF treatment.The economic optimal N rate(EONR)of the OF,TF,and MF was 145.6,147.2,and 144.9 kg ha^(-1) in 2019,and 206.4,186.4,and 146.0 kg ha^(-1) in 2020,respectively.The apparent soil N loss at EONR of the OF,TF,and MF were 97.1-100.5,78.5-79.3,and 50.5-68.1 kg ha^(-1),respectively.These results support MF as a one-time N application method for delivering high yields and economic benefits,with low N input requirements within film mulching spring maize system on the Loess Plateau.

Long-term cattle manure application to saline-sodic soil increases maize yield by decreasing key obstacle factors in the black soil region of Northeastern China

Poor soil physical properties, serious salinization and low soil nutrients are the limiting factors for crop yield in saline-sodic soil. Long-term cattle manure application is an important measure that can affect the physicochemical properties and increase the maize yield of saline-sodic soil. This experiment included five treatments according to the history of cattle manure application: a control treatment with no cattle manure (CK) and treatments with cattle manure application for 14 years (14 a), 17 years (17 a), 20 years (20 a), and 25 years (25 a). The results indicated that compared with the CK treatment, long-term cattle manure application to saline-sodic soil resulted in significant increases in soil organic matter (SOM), soil total nitrogen (TN) and available nutrients at the 0-20 cm and 20-40 cm depths (p<0.05). The soil physical properties improved significantly, and cattle manure application significantly decreased the soil bulk density (ρb) and soil density (ρd) and increased the soil total porosity (ft) and water-holding capacity (WHC). With the number of years of cattle manure application, the soil pH, electrical conductivity (EC), exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR1:5) decreased significantly, and the maize yield gradually increased over time from 8690 kg/hm2 in the CK treatment to 14 690 kg/hm2 in the 25a treatment. There were significant differences among all treatments (p<0.05). The results showed that long-term cattle manure application decreased the soil ρb and saline-alkaline properties, which was the main factor that affected the maize yield in the saline-sodic soil, especially for soil ρb.

Assessing the Impacts of Climate Change and Variability on Maize (Zea mays) Yield over Tanzania

This study aimed at understanding the impacts of the seasonal hydroclimatic variables on maize yield and developing of statistical crop model for future maize yield prediction over Tanzania. The food security of the country is basically determined by availability of maize. Unfortunately, agriculture over the country is mainly rain fed hence highly endangered by the detrimental consequences of climate change and variability. Observed climate data was acquired from Tanzania Meteorological Authority (TMA) and Maize yield data from Food and Agriculture Organization (FAO). The study used the Mann-Kendall test and Sen’s slope for trend and magnitude detection in minimum, maximum temperature and rainfall at the 95% confidence level. The results have shown that rainfall is decreasing over the country and especially during the growing season but increasing during short rains season. Characteristics of seasonal climatic variables, cycle during growing period were linked to maize yield, and high (low) yield was reported during anomalous wet (dry) growing seasons. This portrays seasonal dependence of maize production. Statistical crop model was built by aggregating spatial regions that have statistically significant relation with maize yield. Results show that, 58.8% of yield variance is linked to seasonal hydroclimate variability. Rainfall emerged as the dominant predictor variable for maize yield since it accounts for 44.1% of yield variance. The modeled and observed yields exhibit statistically substantial relationship (r = 0.78) hence depicting high credence of the built statistical crop model. Also, the results revealed a decreasing trend in Maize yield with further Lessing trend is projected to proceed in the future. This calls for adaptation and implementation of appropriate regional measures to raise maize production in order to feed the burgeoning human population amidst climate change.

Modeling the effects of plastic film mulching on irrigated maize yield and water use efficiency in sub-humid Northeast China

In sub-humid Northeast China,plastic film mulching(PFM)is increasingly used with drip irrigation system in maize(Zea mays L.)to cope with seasonal droughts and low temperatures during seedling stage.Although there were several studies showing the benefits of PFM on maize production in the region,quantification of the effects of PFM in sub-humid Northeast China are still lacking.Hybrid-Maize model has a special version that can not only simulate the effects of PFM on reduction of soil evaporation and rise of topsoil temperature,but also simulate the effects of PFM on crop development and other physiological processes.This paper reports how to verify the Hybrid-Maize model against observations and then applying the model to quantify effects of PFM on grain yield and water use efficiency(WUE)under irrigated scenarios.The Hybrid-Maize model was added the heating effects of PFM on rising surface-soil temperature and promoting subsequent crop development by establishing equations between surface-soil temperature and air temperature before V6 stage.A 3-year field experiment including maize growth and yield data measured at a drip-irrigated field in Heilongjiang Province was used to serve the model calibration.The simulated results indicated that the Hybrid-Maize model performed well in simulation of seasonal soil water storage and in-season aboveground dry matter in three years,but overestimated the leaf area index(LAI)for both treatments and underestimated the final aboveground dry matter at maturity for mulched treatments.Although the Hybrid-Maize model overestimated the grain yield and WUE,it did still reflect the effects of PFM on increasing grain yield and WUE during the three growing seasons.The average simulated grain yield and WUE for mulched treatments were 8%and 13%greater compared to non-mulched treatments using 30 years weather data,which were in agreement with observations that average grain yield and WUE was 11%and 14%increased by PFM,respectively.For evapotranspiration(ET),the average simulated ET for mulched treatments was 22 mm less than non-mulched treatments mainly due to less soil evaporation.For simulated irrigation requirements,at most 69 mm of irrigation water could be saved by PFM.In conclusion,PFM with drip irrigation could improve irrigated maize production in sub-humid Northeast China.

Degradability of biodegradable plastic films and its mulching effects on soil temperature and maize yield in northeastern China

Plastic film is an important resource in agricultural production,but it takes hundreds of years to degrade completely in natural environment.The large-scale use of plastic film will inevitably lead to serious environmental pollution.One way to solve the problem is to develop a substitutable mulching film,such as a biodegradable film that can ultimately be decomposed to water,carbon dioxide,and soil organic matter by micro-organisms.In this study,a 2-year experiment was conducted to determine the degradation properties of a biodegradable plastic film,including degradation rate,surface microstructure,tensile strength and elongation at break,and the effects of different mulching treatments on soil temperature and maize yield.The mulching experiment was conducted with three different biodegradable plastic films with different degradation rates,using a common plastic film and a non-mulched treatment as control.With the addition of the additives for degradation in the biodegradable plastic films,the degradation rates increased significantly,which were 7.2%-17.8%in 2017 and 18.1%-35.2%in 2018 after maize harvesting.However,the degradation occurred mainly on the ridge side.The decrease in tensile strength and elongation was proportional to the degradation rate of the degradable film.The SEM results indicated that the surface microstructures of the biodegradable films were loose and heterogeneous after maize harvesting.Biodegradable plastic film mulching increased the soil temperature at soil depths of 5 cm,15 cm,and 25 cm,over the maize’s entire growth period,by 3.1℃-3.2℃ in 2017 and 1.2℃-2.1℃ in 2018 compared with the non-mulched treatment.The biodegradable plastic film increased the maize yield by 10.4%-14.3%in 2017 and 11.6%-24.7%in 2018.The soil temperature and maize yield increases were statistically significant;however,with respect to maize qualities,there were no statistically significant increases among the five treatments.This study shows that biodegradable plastic film can be used as a substitute for common plastic film.However,the ingredients in biodegradable plastic films should be improved further to ensure that they can be degraded completely after crop harvest.

Developing a process-based and remote sensing driven crop yield model for maize(PRYM–Maize) and its validation over the Northeast China Plain

Spatial dynamics of crop yield provide useful information for improving the production. High sensitivity of crop growth models to uncertainties in input factors and parameters and relatively coarse parameterizations in conventional remote sensing(RS) approaches limited their applications over broad regions. In this study, a process-based and remote sensing driven crop yield model for maize(PRYM–Maize) was developed to estimate regional maize yield, and it was implemented using eight data-model coupling strategies(DMCSs) over the Northeast China Plain(NECP). Simulations under eight DMCSs were validated against the prefecture-level statistics(2010–2012) reported by National Bureau of Statistics of China, and inter-compared. The 3-year averaged result could give more robust estimate than the yearly simulation for maize yield over space. A 3-year averaged validation showed that prefecture-level estimates by PRYM–Maize under DMCS8, which coupled with the development stage(DVS)-based grain-filling algorithm and RS phenology information and leaf area index(LAI), had higher correlation(R, 0.61) and smaller root mean standard error(RMSE, 1.33 t ha^(–1)) with the statistics than did PRYM–Maize under other DMCSs. The result also demonstrated that DVS-based grain-filling algorithm worked better for maize yield than did the harvest index(HI)-based method, and both RS phenology information and LAI worked for improving regional maize yield estimate. These results demonstrate that the developed PRYM–Maize under DMCS8 gives reasonable estimates for maize yield and provides scientific basis facilitating the understanding the spatial variations of maize yield over the NECP.

Effect of biochar application method and amount on the soil quality and maize yield in Mollisols of Northeast China

There have been many studies on soil quality and crop yield using different biochar application amounts,but few studies have focused on the combination of different methods and amounts of biochar application in moderately degraded Mollisols.In this study,the methods of mixing biochar evenly with the soil of the plough layer(0-20 cm depth)[homogeneous biochar application(HO)]and burying biochar above the soil plow pan(under 20 cm depth)(heterogeneous biochar application(HE))were used to reveal how biochar application methods influenced soil quality,crop yield and agronomic characteristics in moderately degraded Mollisols(soil organic matter(SOM),30.33 g kg^(−1)).The biochar application amounts were 0(control),10(level 1),20(level 2),and 40(level 3)t ha^(−1)in both the HO and HE treatments.The results showed that,compared with control,HO3 significantly increased maize yield in the first year,and HO2,HO3,HE2 and HE3 continuously increased maize yield in the next three years but not significantly.HO1 and HE1 had the lowest maize yield.HO2 tended to delay maize leaf senescence.There was a posi-tive linear relationship between soil quality index(SQI)and biochar application amount in HO.Compared with other treatments,the pH,EC,SOM,available phosphorus,sucrase and catalase activities were highest in HO3.However,the effects of HE on soil quality and crop productivity were limited at first but gradually increased with time.Overall,HO3 was beneficial for improving the soil quality and crop productivity in Mollisols for short-term cultivation(3-year),while HE showed an effect over time.

Understanding yields in alley cropping maize (Zea mays L.) and Cassia siamea Lam. under semi-arid conditions in Machakos, Eastern Kenya

Six seasons of experiments in Machakos, Kenya, revealed that above about 150 mm of rainfall, maize yields per row in alley cropped “replacement” agroforestry (AF) plots, of Cassia siamea Lam. and maize ( Zea mays, cv. Katumani Composite B), may be expected to exceed those in the control (sole maize) plots. Such yields were insufficient to compensate for the area “lost” to the hedgerows. Below about 150 mm the control plots may be expected to perform better. This result was due to competition for water. Greater association of the fine roots of Cassia and maize was observed in the middle of the alleys than near the hedgerows. Photosynthetic consequences of shading were insignificant relative to other factors. In the alleys, reductions of soil temperature due to shade in the western and eastern maize rows were higher than in the middle row. Soil moisture extraction was higher in the AF than in the control plots. In the AF plots, moisture extraction was greater under the central maize rows than under those nearest the Cassia. Yield patterns followed such soil temperature and soil moisture patterns. Maize transpiration and photosynthetic rates were significantly higher in the control than in the AF plots during a below average rainy season but not during above average rainy seasons. It is concluded that alley cropping under semi arid conditions should be approached differently from the system worked on. It must at least provide strong physical protection of crops and/or soils and have a strong economic incentive to be of interest to the farmers.

Effects of Sowing Periods on Growth and Development,Yield and Quality of Maize in Cold Area

In order to determine the most suitable sowing periods for maize in the cold area of Harbin City,the field test method was adopted.From 2018 to 2019,the main maize variety Xianyu 696 which was planted in Harbin City,Heilongjiang Province,was used as the test material for the six-sowing-period treatment experiments.The sowing period settings were as the followings:April 20(T1),April 24(T2),April 27(T3),May 4(T4),May 11(T5)and May 18(T6).In the experiment,the effects of different sowing periods on the growth and development,yields and quality of maize were studied.The results showed that the maize through T1 treatment had the longest growth period,the lowest height and the highest ear height,and the highest grain protein content.The maize through T6 treatment had the highest height and ear height,as well as the highest starch and oil content.And the grain crude fat,soluble protein,soluble sugar and the moisture content increased and then decreased with the delay of the sowing period.The maize through T4 treatment had the highest content of soluble protein.However,other quality indicators and the number of rows,the length of the bald tip,the number of grains per spike and the weight of 100 grains first increased and then decreased with the delay of the sowing period.The dry matter accumulation through T4 treatment was significantly higher than the ones through five treatments,and the 100-kernel weight and other ear-grain traits were the highest,the maizes through T4 treatment increased the yield by 21.54%compared with that through T1 treatment.Thus,the most suitable sowing period for the maize in the cold area of Harbin City was from May 4 to May 11.It provided technical supports for guiding maize planting in the cold area of Harbin City.

How delaying post-silking senescence in lower leaves of maize plants increases carbon and nitrogen accumulation and grain yield

Planting maize at high densities leads to early leaf senescence,and the resulting reduction in the number of lower leaves affects the plant’s root function and lowers its grain yield.However,the nature of the process by which lower leaf senescence affects biomass accumulation and grain yield formation in maize is not clear.This study aimed to shed light on how these factors are related by investigating the effects of the plant growth regulator 6-benzyladenine(6-BA)on the senescence of lower leaves of maize plants.In two maize cultivars planted at densities of 67,500(low density,LD)and 90,000(high density,HD)plants ha^(-1),plants treated with 6-BA maintained a high green leaf area index(LAI)longer than control(CK)plants,enabling them to maintain a higher photosynthetic rate for a longer period of time and produce more biomass before reaching physiological maturity.Spraying the lower leaves of maize plants with a 6-BA solution increased the distribution of;C-photosynthates to their roots,lower leaves and bracts,a result that can be ascribed to a decreased retention of;C-photosynthates in the stem and grain.In both seasons of the experiment,maize plants treated with 6-BA accumulated more N in grain and maintained a higher N content in roots and leaves,especially in lower leaves,than CK.Increased C assimilation in the lower leaves may explain why N uptake in plants subjected to the 6-BA treatment exceeded that in CK plants and why both photosynthesis rate and dry matter accumulation were maintained throughout grain filling.Our results suggest that a suitable distribution of C and N in leaves post-silking may maintain plant root function,increase N use efficiency,maximize the duration of high LAI,and increase grain yield.

Identifying the critical phosphorus balance for optimizing phosphorus input and regulating soil phosphorus effectiveness in a typical winter wheat-summer maize rotation system in North China

Phosphorus(P)is a nonrenewable resource and a critical element for plant growth that plays an important role in improving crop yield.Excessive P fertilizer application is widespread in agricultural production,which not only wastes phosphate resources but also causes P accumulation and groundwater pollution.Here,we hypothesized that the apparent P balance of a crop system could be used as an indicator for identifying the critical P input in order to obtain a high yield with high phosphorus use efficiency(PUE).A 12-year field experiment with P fertilization rates of 0,45,90,135,180,and 225 kg P_(2)O_(5)ha^(-1)was conducted to determine the crop yield,PUE,and soil Olsen-P value response to P balance,and to optimize the P input.Annual yield stagnation occurred when the P fertilizer application exceeded a certain level,and high yield and PUE levels were achieved with annual P fertilizer application rates of 90-135 kg P_(2)O_(5)ha^(-1).A critical P balance range of 2.15-4.45 kg P ha^(-1)was recommended to achieve optimum yield with minimal environmental risk.The critical P input range estimated from the P balance was 95.7-101 kg P_(2)O_(5)ha^(-1),which improved relative yield(>90%)and PUE(90.0-94.9%).In addition,the P input-output balance helps in assessing future changes in Olsen-P values,which increased by 4.07 mg kg^(-1)of P for every 100 kg of P surplus.Overall,the P balance can be used as a critical indicator for P management in agriculture,providing a robust reference for limiting P excess and developing a more productive,efficient and environmentally friendly P fertilizer management strategy.

Historical trends in maize morphology from the 1950s to the 2010s in China

The morphology of the plant and ear is a preliminary selection characteristic in breeding new varieties of maize.As new maize cultivars were developed from the 1950s through the 2010s in China,most had changes in both plant and ear morphological characteristics that contributed substantially to maize yield gains.Over the seven decades,plant and ear height fluctuated with a small increase from the 1950s to 2000s,and then a decrease in the 2010s,while the ear ratio and internodes length below the ear decreased significantly.Leaf angles became significantly more upright,especially for the leaves above the ear,and the leaf area per plant improved markedly.Leaf orientation increased from the 1950s to the 2000s then decreased in the 2010s.Tassel size and the anthesis-silking interval were both reduced substantially.Ear diameter,kernel number,and kernel weight increased from the 1950 to the 2000s,then decreased in the 2010s under the same cultivation conditions.We found that modern maize hybrids have a lower plant height,ear height and ear ratio which increased lodging resistance,a more erect leaf which increased high-density planting tolerance,and smaller ears and kernels which facilitated rapid dehydration during late grain filling.These morphological selection criteria,which are suitable for mechanized operations,are proposed as the focus for future maize breeding.

Identification of Common Maize Diseases and Their Prevention and Control Methods

Agriculture is the basic industry of China's economic development,and maize is an important part of the agricultural economy.With the increase of global environmental warming and industrial pollution,as well as the adjustment of agricultural planting structure and the transformation of farming and cultivation methods in China,the breeding of maize varieties has been accelerated,and the planting area has increased rapidly,resulting in the condition that the occurrence of maize diseases and pests has been increasing.The damage of some minor diseases continued to increase nationwide or in local areas,and rose to major diseases,and some new diseases appeared in production,posing a threat to the safe production of maize.This paper summarized the occurrence status of important maize diseases in China,and put forward corresponding prevention and control countermeasures.

Economically Optimal Rates and Nutrients Use Efficiency Indices of Maize to the Application of Different Rates of Nutrients in Central Rift Valley of Ethiopia

The use of balanced fertilizers in adequate amount is very important to increase crop productivity and production in Ethiopia. The study was executed to quantify maize (Zea mays L.) grain yield response to different rates of nitrogen (N), phosphorus (P), potassium (K) and sulfur (S) under balanced fertilization of other nutrients. On farm trials were conducted at seven sites on 8 farmers’ fields in Negele Arsi districts, west Arsi zone of Oromia region for three consecutive cropping seasons (2014-2016). Six rates of N, P, S and eight rates of K treatments established separately for each nutrient were laid out in randomized complete block (RCB) design with three replicates per farm. Nutrient response function modelling showed that 184, 20 and 80 kg•ha−1 were the agronomic optimum rate for N, P, and K, respectively. Mean agronomic efficiency (AE) of N, P and K were recorded at the lower rates of these nutrients, application of 46, 10 and 20 kg•ha−1 N, P and K resulted in 19.1, 61.0, and 24 kg additional grain yield•kg−1 N, P and K, respectively. Also, the mean partial factor productivity (PFP) of N, P and K were 77.6, 370 and 158 kg additional grain•kg−1 applied N, P and K respectively. Economically optimal rate (EOR) of N, P and K were 48 - 114 kg•ha−1 N with CP 8 - 3.5, 12 - 20 kg•ha−1 P with CP 18 - 4.5 and 32 - 53 kg•ha−1 K with CP 8-4, from these rates net returns of US$487.23 - 143.30, US$698.16 - 498.3 and US$359.31 - 193.63 could be obtained respectively. To conclude, application of 84, 12 and 40 kg•ha−1 N, P and K could be recommended for the production of maize.