Effects of Five Years Adoption of No-Tillage Systems for Vegetables Crops in Soil Organic Matter Contents

Vegetables productions systems are done normally with intense soil tillage causing a strong decline of soil quality. Use of conservation systems can be an alternative to recover this quality. In order to evaluate the effects of such systems on soil organic matter, an experiment has been conducted in randomized blocks design and factorial scheme 3 × 2: three soil management systems (no-tillage;reduced tillage and conventional tillage) and two cover crops (maize single;and intercropping maize with gray velvet bean—Stizolobium niveum);and repeated measures over time. Soil samples were collected before the implementation of the experiment and at the end of each crop cycle until the fifth crop cycle. Carbon associated with humic substances is also determined in 0 - 5 cm, 5 - 10 cm and 10 - 30 cm at the end of the last crop cycle. The SOM content was higher in RT (48.34 g·kg-1) than in the CT (39.48 g·kg-1) at the end of the fifth crop cycle. SOM content in NT (44.92 g·kg-1) was statistically equal to RT and CT, during the same period. In 0 - 5 cm, carbon contents associated to the humic substances present the same behavior of SOM contents in 0 - 10 cm. Probably these results are associated with the capacity of each system to improve superficial contents of SOM stable fractions. It follows that the conservation systems used are alternatives to the cultivation vegetables in order to improve soil organic matter contents.

Effects of Nitrogen Application Rate, Density and Seedling Age on Dry Matter Accumulation of No-tillage Rape in Seedling Stage

[Objective] The aim of the research was to find the optimal nitrogen application rate, density and seedling age for no-tillage rape in seedling stage. [Method] With the D-optimal quadratic regression design for three factors, the 310 scheme was designed to study the effects of nitrogen application rate, density and seedling age on dry matter accumulation of no-tillage rape in seedling stage. [Result] With the increase of nitrogen application rate, density and seedling age, the dry matter content appeared like a parabola, increasing firstly and then declining. The change of nitrogen application rate caused greater influence than that of density and seedling age; the interaction effects between nitrogen application rate and density were greater than that between nitrogen application rate and seedling age as well as between density and seedling age. [Conclusion] Considered comprehensively, the dry matter content of no-tillage rape in seedling stage reached the highest level (4 768.2 kg/hm2) when the nitrogen application rate, the density and the seedling age were 195 kg/hm2, 93 000 plants/hm2 and 33 d, respectively.

Effects of Planting Density, Duration of Disclosing Plastic Film and Nitrogen Fertilization on the Growth Dynamics of Rapeseed under No-tillage Cultivation

[ Objective] This study was to understend the optimized combination of planting density, duration of disclosing plastic film and nitrogen fertilization under no-tillage cultivation. [ Method] Quadratic polynomial regression and saturated D-optimal design were employed to investigate the effects of planting density, duration of disclosing plastic film and nitrogen fertilization on the dynamics growth of rapeseed under no-tillage cultivation.[ Result] Within the experimental range, the growth dynamics of no-tillage cultivated rapeseed assumed a rise-fall tend. For the effects to the growth dynamics of no-tillage cultivated rapeseed, nitrogen application amount was higher than planting density and duration of disclosing plastic film. The interaction effect between planting density and duration of disclosing plastic film was higher than that between nitrogen application amount and planting density, and between nitrogen application amount and duration of disclosing plastic film. [ Conclusion] The optimized combination of these factors for dynamic growth of rapeseed under no-tillage cultivation was determined to be： planting density of per hectare 154 925 individuals, duration of disclosing plastic film of 110 d, nitrogen application amount of 315 kg/hm^2.

A Comparative Study on No-tillage Late DirectSowing Varieties of Brassica napus L. in Western Sichuan Plain

[Objective] There are continuous rainy days in Western Sichuan Plain in autumn. In order to avoid the impact of wet injury in sowing period, new varieties of Brassica napus L. with low erucidic acid and glucosinolate content which are suitable for no-tillage late direct-sowing in Western Sichuan Plain were screened in this study. [Method] Ten major varieties of Brassica napus L. were screened by randomized block design and triplicated plot test with no-tillage late direct-sowing and straw mulching for comparative experiment. [Result] ‘Chuanyou 58＇, ‘Huayouza 10＇and ‘Ningza 11＇ have high yield（per unit area yield above 3 000 kg/hm2）, excellent comprehensive characters, short growth period, high resistance and high quality;‘Huayouza 13＇ and ‘Zheshuang 3＇ have high yield potential（per unit area yield above 2 775 kg/hm2）, high resistance, high quality and moderate growth period; other varieties have extremely significant yield reduction, poor comprehensive characters and low resistance compared with control. [Conclusion] Excellent varieties of Brassica napus L. in the middle and lower reaches of Yangtze River such as ‘Huayouza10＇, ‘Ningza 11＇, ‘Huayouza 13＇ and ‘Zheshuang 3＇ can be successfully introduced and applied for large-area cultivation in Western Sichuan Plain.

Experimental Study on No-tillage Cultivation of Flowering Chinese Cabbage in Rice Winter Fallow Fields

The research made comparisons on no-tillage cultivation and ploughing cultivations of Flowering Chinese cabbage on one-season paddy fields and explored the effects of no-tillage cultivation of Flowering Chinese cabbage on survival rate, insect damages, production cost, yield and benefits of plants. The results indicated that no-tillage cultivation reduced the injured rate of Flowering Chinese cabbage by cutworms, and production cost, but crop yield and output value declined as well. Specifically, yield in the treatment as per no-tillage cultivation lowered by 10.3% and 11.9% compared with the treatments by machine-based ploughing and manual ploughing, and the production interests declined by 11.9% and 11.1%, accordingly.

Effects of Subsoiling on Soil Moisture Under No-Tillage for Two Years

In order to improve the water use efficiency under conservation tillage, the effects of subsoiling on soil moisture under notillage were studied. An experiment of 40 cm subsoiling in a field kept under no-tillage for 2 years was operated from 2005 to 2006. Based on the data of the soil moisture and crop yield, the physical basis of subsoiling for water conservation and yield increase was analyzed. The results showed that the soil water storage under subsoiling, from the soil surface to a depth of 100 cm was more than that under no-tillage for the growth season. In the 0-100 cm soil depth, the soil moisture in 50-100 cm depth under subsoiling was more compared with no-tillage, which increased when it＇s drought and decreased when it＇s rainy with the increase in soil depth. Compared with no-tillage, subsoiling could reduce the water consumption of oats in the 0-50 cm depth and increase the water consumption in the 50-100 cm depth. Also, subsoiling increased the yield by 18.29% and the water use efficiency by 16.8% in a two-year average. The effects of subsoiling on water conservation and yield increase were affected by precipitation, and a well-proportioned rainfall was better to increase yield and water use efficiency. Meanwhile, subsoiling decreased bulk density, which increased with the available precipitation. Subsoiling under no-tillage is the effective rotation tillage to contain more soil moisture and improve water use efficiency in ecotone of North China.

Differentiation of Soil Fauna Populations in Conventional Tillage and No-Tillage Red Soil Ecosystems

In a field experiment, the populations of major soil fauna groups including earthworms, enchytraeids,arthropods and nematodes were examined in conventional tillage (CT) and no-tillage (NT) red soil ecosystems to evaluate their responses to tillage disturbance. Earthworms, macrry and micro-arthropods were stimulated under NT with earthworms showing the highest population increase by four times, while enchytraeids and nematodes favored CT system, predicting certain adaptability of these animals to plow-disturbed soil environment. On the basis of relative response index it was found that soil fauna was more sensitive to tillage than soil resource base (C and N pools) and microflora. The population structure of soil fauna was also affected by tillage treatments. Analysis on nematode trophic groups showed that bacteria-feeding and plant parasitic nematodes were more abundant in CT soil whereas the proportions of fungivores and omnivorepredators increased in NT soil. Possible reasons for the differentiation in both size and structure of the fauna population were discussed and the ecological significance involved in these changes was emphasized.

Effect of experimental warming on soil respiration under conventional tillage and no-tillage farmland in the North China Plain

Understanding the response of soil respiration to global warming in agro-ecosystem is crucial for simulating terrestrial carbon （C） cycle. We conducted an infrared warming experiment under conventional tillage （CT） and no-tillage （NT） farmland for winter wheat and summer maize rotation system in North China Plain （NCP）. Treatments include CT with and without warming （CTW and CTN）, NT with and without warming （NTW and NTN）. The results indicated that warming had no sig- nificant effect on soil moisture in irrigated farmland of NCP （P〉0.05）. The elevated average soil temperature of 1.1-116℃ in crop growing periods could increase annual soil CO2 emission by 10.3% in CT filed （P〉0.05）, but significantly increase it by 12.7% in NT field （P〈0.05）, respectively. The disturbances such as plowing, irrigation and precipitation resulted in the obvious soil CO2 emission peaks, which contributed 36.6-40.8% of annual soil cumulative CO2 emission. Warming would enhance these soil CO2 emission peaks; it might be associated with the warming-induced increase of autotrophic respiration and heterotrophic respiration. Compared with un-warming treatments, dissolved organic carbon （DOC） and soil microbial biomass carbon （MBC） in warming treatments were significantly increased by 11.6-23.4 and 12.9-23.6%, respectively, indicating that the positive responses of DOC and MBC to warming in both of two tillage systems. Our study highlights that climate warming may have positive effects on soil C release in NCP in association with response of labile C substrate to warming.

Inter-annual changes in the aggregate-size distribution and associated carbon of soil and their effects on the straw-derived carbon incorporation under long-term no-tillage

Converting from conventional tillage to no-tillage influences the soil aggregate-size distribution and thus soil organic carbon （SOC） stabilization. However, the dynamics of soil aggregation and the straw-derived carbon （C） incorporation within aggregate fractions are not well understood. An experiment was established in 2004 to test the effects of two treatments, no-tillage with residue （NT） and conventional tillage without residue （CT）, on the soil aggregate-size distribution and SOC stabilization in a continuous maize （Zea mays L.） cropping system located in the semiarid region of northern China. Soil samples were collected from the 0-10 cm layer in 2008, 2010 and 2015, and were separated into four aggregate-size classes （〉2, 0.25-2, 0.053-0.25, and 〈0.053 mm） by wet-sieving. In each year, NT soil had a higher proportion of macroaggregates （i.e., 〉2 and 0.25-2 mm） and associated SOC concentration compared with CT. Additionally, to compare straw-derived C incorporation within NT and CT aggregate fractions, ^13C-labeled straw was incubated with intact NT and CT soils. After 90 days, the highest proportion of 13C-labeled straw-derived C was observed in the 〉2 mm fraction, and this proportion was lower in NT than that in CT soil. Overall, we conclude that long-term continuous NT increased the proportion of macroaggregates and the C concentration within macroaggregates, and the physical protection provided by NT is beneficial for soil C sequestration in the continuous maize cropping system in semiarid regions of northern China.

Characterization of Leaf Photosynthetic Properties for No-Tillage Rice

A study was conducted to determine the influence of no-tillage cultivation on leaf photosynthesis of rice plants under field conditions. Experiments with the treatments, no-tillage and conventional tillage were carried out at three locations （Jiaxing, Hangzhou and Xiaoshan, Zhejiang Province, China） for two years （2005 and 2006）. Grain yield was constant in Jiaxing, but slightly higher in Hangzhou and Xiaoshan under no-tillage cultivation than that under conventional cultivation. In comparison with the conventional cultivation, no-tillage cultivation showed less biomass accumulation before heading and higher capacity of matter production during grain filling. A significantly higher leaf net photosynthetic rate was observed for the plants under no-tillage than for those under conventional tillage. The fluorescence parameter （Fv/Fm） in leaf did not show any difference between the two cultivations. The effect of cultivation management on transpiration rate （Tr） and SPAD value of rice leaf was dependent on the location and year.

Growth Characteristics and Yield of Late-Season Rice under No-tillage and Non-flooded Cultivation with Straw Mulching

A long-term field experiment （started at 2003） was conducted to determine the effects of different dce cultivation methods on growth characteristics and grain yield of late-season rice under double-rice cropping system in seasonal drought region of southeast China （Yujiang County, Jiangxi Province）. The rice cultivation methods included no-tillage and flooded rice cultivation （N-F）, no-tillage and non-flooded rice cultivation with straw mulching （N-SM）, and no-tillage and non-flooded rice cultivation without straw mulching （N-ZM）. There was no significant difference in rice grain yield between the N-SM and N-F treatments. However, the rice grain yields in the N-SM and N-F treatments were significantly higher than that in the N-ZM treatment. The late-season rice plants in the N-SM treatment had significantly higher numbers of effective panicles and total grains per hill compared with those in the N-ZM treatment. The above-ground dry matter of late-season rice was similar between the N-SM and N-F treatments. Compared with the N-F treatment, the N-ZM and N-SM treatments significantly decreased the leaf area at the heading stage. Moreover, the N-SM treatment could significantly increase total root length and root tip number at the grain-filling stage compared with the N-ZM treatment.

Suppression of weeds and weed seeds in the soil by stubbles and no-tillage in an arid maize-winter wheat-common vetch rotation on the Loess Plateau of China

Reduced tillage provides ecological and economic benefits to arable land on the Loess Plateau of China, where soil erosion has long been a serious problem and soil water availability is largely restricted. However, high abundances of weeds in reduced tillage systems cause significant yield losses. In this study, we explored the effects of no-tillage and stubble retention on the number and density of weeds and weed seeds in a 12-year maize-winter wheat-common vetch rotation on the Loess Plateau. Four treatments including conventional tillage, no-tillage, conventional tillage＋stubble retention and no-tillage＋stubble retention were designed and applied. We found that no-tillage increased the number of weed species and weed density in most of the crops, while stubble retention decreased weed density in maize and tended to suppress weeds in both no-tillage treatments（no-tillage and no-tillage＋stubble retention）. No-tillage led to an increase in the number of weed species in the weed seedbank and tended to increase seed density during the spring growth of winter wheat, but it decreased seed density during post-vetch fallow. Stubble retention tended to reduce seed density during the spring growth of winter wheat and post-vetch fallow. We concluded that no-tillage can promote weeds in the experimental crop rotation, while stubble retention suppresses weeds in untilled fields. The combined effects of stubble retention and no-tillage on weed suppression varied among the three crops. Based on these results, we recommend stubble retention in untilled legume-crop rotations on the Loess Plateau to improve the control of weeds.

Effects of residue management and nitrogen fertilizer rates on accumulation of soil residual nitrate and wheat yield under no-tillage system in south-west of Iran

Conservation tillage,residue management and optimizing nitrogen(N)fertilization are important stra-tegies for soil and water conservation and sustainability of agricultural systems.In order to evaluate the effects of various residue management methods and N fertilizer rates on some soil quality indicators,accumulation of residual soil nitrate,and wheat yield under no till system,a split-plot experiment was arranged in a randomized complete block design with three replications.Main plots were three residue management methods,including retaining(R.M1),removing(R.M2)and shredding(R.M3)of corn res-idues.The subplots consisted of four N fertilizer rates,100(N1),150(N2),200(N3),and 250(N4)kg N ha^(-1) from urea source.The results showed that soil organic carbon and total N in R.M1 and R.M3 treatments increased at the depth of 0-15 cm as compared to R.M2.The maximum accumulation of soil nitrate was observed in R.M1 x N4 and R.M3 x N4 interactions at the soil depth of 60-cm.The results of this study showed that R.M1 x N3 and R.M3 x N3 interactions had a greater impact on wheat yield than the sole effect of R.M1 or R.M3.According to our findings,application of 200 kg N ha^(-1) in combination with R.M1 which had once less tractor passing for mechanical shredding than R.M3,can contribute effectively to improve soil quality indicators,control soil residual nitrate and subsequently produce more wheat grain yield in the south-west of Iran.

Long-Term No-Tillage Direct Seeding Mode for Water-Saving and Drought-Resistance Rice Production in Rice-Rapeseed Rotation System

To study the effects of long-term no-tillage direct seeding mode on rice yield and the soil physiochemical property in a rice-rapeseed rotation system, a comparative experiment with a water-saving and drought-resistance rice （WDR） variety and a double low rapeseed variety as materials was conducted under no-tillage direct seeding （NTDS） mode and conventional tillage direct seeding （CTDS） mode for four years, using the CTDS mode as the control. Compared with the CTDS mode, the actual rice yield of WDR decreased by 8.10% at the first year, whereas the plant height, spikelet number per panicle, spikelet fertility, 1000-grain weight, grain yield, actual yield, and harvest index increased with no-tillage years, which led to the actual yield increase by 6.49% at the fourth year. Correlation analysis showed that the panicle length was significantly related to the actual yield of WDR. Compared with the CTDS mode in terms of the soil properties, the pH value of the NTDS mode decreased every year, whereas the contents of soil organic matter and total N of the NTDS mode increased. In the 0-5 cm layer of the NTDS mode, the soil bulk decreased, whereas the contents of soil organic matter, total N, and available N increased. In the 5-20 cm layer of the NTDS mode, the available N and K decreased, whereas the soil bulk, contents of soil organic matter, and total N increased. In summary, the NTDS mode increased the rice yield, and could improve the paddy soil fertility of the top layer.

No-tillage effects on grain yield and nitrogen requirements in hybrid rice transplanted with single seedlings: Results of a long-term experiment

This study was conducted to determine whether,and if so how,the grain yield and nitrogen(N) requirements of hybrid rice transplanted as single seedlings are affected by no-tillage(NT) practices.A fixed field experiment was done at the Experimental Farm of Hunan Agricultural University in Changsha,Hunan Province,China,from 2004 to 2014.Grain yield and yield attributes(panicle number per m2,spikelet number per panicle,spikelet filling percentage,grain weight,total biomass,and harvest index) were evaluated as well as the N-use characteristics(total N uptake,internal N-use efficiency,and N requirements) of hybrid rice transplanted as single seedlings comparing NT with conventional tillage(CT).A significant finding was that there were no significant differences in grain yield,yield attributes,and N-use characteristics between CT and NT.Averaged across the 11 years,grain yield and N requirements were 9.51 t ha^(-1) and 20.2 kg t^(-1) under CT and 9.33 t ha^(-1) and 20.0 kg t^(-1) under NT,respectively.There were significant yearly variations in grain yield,yield attributes,and N-use characteristics observed under both CT and NT.The yearly variation in grain yield was related to simultaneous changes in spikelet number per panicle,grain weight,total biomass,and harvest index.Also,it was found that grain yield was positively correlated with internal N-use efficiency but negatively correlated with N requirements.It is concluded that grain yield and N requirements in hybrid rice when transplanted as single seedlings are not affected adversely by NT.The results of this study suggest that(1) compatible relationships among yield attributes can be established in hybrid rice that is transplanted as single seedlings,and(2) higher grain yield and higher N-use efficiency can be concurrently achieved in hybrid rice transplanted as single seedlings.

Physiological Mechanism of High and Stable Yield of No-tillage Cast-transplanted Rice

Four years' successive comparative experiments showed that no-tillage cast-transplanted rice (NTCTR), compared with conventional tillage cast-transplanted rice (CK), grew slower and produced less tillers at the early growing stage; but, it had shorter ineffective tillering time, less nutrition consumption, stronger individual growth and more uniform growth between individuals and the colony. These characteristics contribute to the increase not only in the productive tiller percentage but also in the ear quality. Furthermore, the flag leaf of NTCTR had higher photosynthetic rate during the filling stage and no early senescence phenomenon at the late stage, which facilitated the accumulation and the transportation of carbohydrates and improved grain setting rate.

Effects of Different Factors on Yield of No-tillage Direct-seeding Rapeseed

The effects of different sowing dates,plant densities and nitrogen applica- tion amounts on yield of no-tillage direct seeding rapeseed were studied. The re- sults indicated that the optimum sowing date was from October 1 to 15, the opti- mum plant density was 450 000-750 000 plant/hm2, the optimum nitrogen applica- tion amount was 270 kg/hm2 in the southeast of Hubei province.

Effects of Organic Fertilizer Application Amount on Seedling Quality under No-tillage Semi-Solid State Direct Seeding

With early rice variety Zhongzao 39 as test material,this paper investigated the effects of organic fertilizer application rate on seedling quality under no-tillage semi-solid state direct seeding.The results showed that the seedling quality of no-tillage semi-solid direct seeding was better than that of traditional direct seeding,and different application rates of organic fertilizer under no-tillage semi-solid direct seeding also had signi ficant effects on seedling emergence rate,dry matter weight in ground and underground,stem base width,root activity,chlorophyll content and seedling growth index of rice seedlings.When the organic fertilizer dosage was A4(0.10∶1),it was most beneficial to the growth and development of rice seedlings under no-tillage semi-solid state direct seeding,it could effectively improve the quality of rice seedlings and enhance their resistances,the cultivated seedlings could lay a good foundation for high yield of rice in late stage.

Residue Return Effects Outweigh Tillage Effects on Soil Microbial Communities and Functional Genes in Black Soil Region of Northeast China

Conservation tillage as an effective alternative to mitigate soil degradation has attracted worldwide attention,but the influences of conservation tillage on soil microbial community and especially function remain unclear.Shotgun metagenomics sequencing was performed to examine the taxonomic and functional community variations of black soils under three tillage regimes,namely no-tillage with residue(maize straw)return(NTS),moldboard plow with residue return(MPS),and moldboard plow without residue return(MPN)in Northeast China.The results revealed:1)Soil bacterial and archaeal communities differed significantly under different tillage regimes in contrast to soil fungal community.2)The overlay of less tillage and residues return under NTS led to unique soil microbial community composition and functional composition.Specifically,in contrast to other treatments,NTS increased the relative abundances of some taxa such as Bradyrhizobium,Candidatus Solibacter,and Reyranella,along with the relative abundances of some taxa such as Sphingomonas,Unclassified Chloroflexi and Nitrososphaera decreased;NTS had a unique advantage of increasing the relative abundances of genes involved in‘ATP-binding cassette(ABC)transporters’and‘quorum sensing(QS)’pathways,while MPN favored the genes involved in‘flagellar assembly’pathway and some metabolic pathways such as‘carbon’and‘glyoxylate and dicarboxylate’and‘selenocompound’metabolisms.3)Significantly different soil bacterial phyla(Acidobacteria,Gemmatimonadetes,and Chloroflexi)and metabolic pathways existed between MPN and another two treatments(NTS and MPS),while did not exist between NTS and MPS.4)Dissolved organic carbon(DOC)and soil bulk density were significantly affected(P<0.05)by tillage and accounted for the variance both in microbial(bacterial)community structure and functional composition.These results indicated that a change in tillage regime from conventional to conservation tillage results in a shift of microbial community and functional genes,and we inferred that residue return played a more prominent role than less tillage in functional shifts in the microbial community of black soils.

Estimating Carbon Capture Potential of Fallow Weeds in Rice Cropping Systems

Weeds occurred during the fallow season can well perform the function of carbon(C)capture due to receiving little human disturbance.This study aimed to evaluate the C capture potential of fallow weeds in rice(Oryza sativa L.)cropping systems.A six-region,two-year on-farm investigation and a three-year tillage experiment were conducted to estimate C capture in fallow weeds in rice cropping systems.The on-farm investigation showed that the average mean C capture by fallow weeds across six regions and two years reached 112 g m^(-2).The tillage experiment indicated that no-tillage practices increased C capture by fallow weeds by 80%on average as compared with conventional tillage.The results of this study not only contribute to an understanding of C capture potential of fallow weeds in rice cropping systems,but also provide a reference for including fallow weeds in the estimation of vegetative C sink.