Effects of Tillage Practices on Water Consumption, Water Use Efficiency and Grain Yield in Wheat Field

Water shortage is a serious issue threatening the sustainable development of agriculture in the North China Plain, with the winter wheat （Triticum aestivum L.） as its largest water-consuming crop. The effects of tillage practices on the water consumption and water use efifciency （WUE） of wheat under high-yield conditions using supplemental irrigation based on testing soil moisture dynamic change were examined in this study. This experiment was conducted from 2007 to 2010, with ifve tillage practice treatments, namely, strip rotary tillage （SR）, strip rotary tillage after subsoiling （SRS）, rotary tillage （R）, rotary tillage after subsoiling （RS）, and plowing tillage （P）. The results showed that in the SRS and RS treatments the total water and soil water consumptions were 11.81, 25.18%and 12.16, 14.75%higher than those in SR and R treatments, respectively. The lowest ratio of irrigation consumption to total water consumption in the SRS treatment was 18.53 and 21.88%for the 2008-2009 and 2009-2010 growing seasons, respectively. However, the highest percentage of water consumption was found in the SRS treatment from anthesis to maturity. No signiifcant difference was found between the WUE of the lfag leaf at the later iflling stage in the SRS and RS treatments, but the lfag leaf WUE at these stages were higher than those of other treatments. The SRS and RS treatments exhibited the highest grain yield （9 573.76 and 9 507.49 kg ha-1 for 3-yr average） with no signiifcant difference between the two treatments, followed by P, R and SR treatments. But the SRS treatment had the highest WUE. Thus, the 1-yr subsoiling tillage, plus 2 yr of strip rotary planting operation may be an efifcient measure to increase wheat yield and WUE.

Effects of tillage practices on nutrient loss and soybean growth in red-soil slope farmland

Field experiments were conducted to examine the effect of tillage practices on sediment and nutrient loss and soybean growth under natural rainfall conditions.Three tillage practices were applied:downslope ridge(check),downslope ridge+contour living hedgerow,and cross ridge.Cross ridge tillage reduced surface runoff by 69%and sediment yield by 86%,compared to the check treatment.The downslope ridge with a contour living hedgerow reduced surface runoff by 24%and sediment yield by 53%.Additionally,compared to the check plot,nutrient losses carried by runoff were reduced by over 68%and that carried in the sediment was reduced more than 85%in the cross ridge plot.Nutrient losses in runoff were reduced by 20%to 30%in the downslope ridge and contour living hedgerow plot and those carried in the sediment were reduced by 44%to 57%.Cross ridge tillage soybean yields exceeded those of the downslope ridge and downslope ridge+contour living hedgerow treatments by 16%-18%.Cross ridge tillage could contribute to the prevention sediment and nutrient loss and could improve crop yield,and thus it is recommended to be applied to mild slopes in the red soil region.

Effects of crop residue managements and tillage practices on variations of soil penetration resistance in sloping farmland of Mollisols

Soil penetration resistance(SPR)is one of the major indicators of soil physical properties.Crop residue managements,tillage practices and their interactions exert significant effects on the SPR.However,rare information is available in the sloping farmland of Mollisols.Field experiments were conducted to investigate the variations of the SPR as affected by crop residue managements and tillage practices on the sloping land in Northeast China from 2015 to 2019.The split-plot experiment was arranged with two crop residue managements(removed,REM and retained,RET),and three tillage practices(no tillage,NT;rotary tillage,RT;plow tillage,PT).SPR data in 0-80 cm soil depth was measured at the end of harvest of maize monoculture.Results showed that the two crop residue managements induced significant variations in the SPR at 0-15 cm,15-30 cm and 0-80 cm soil depths under NT,RT,and PT treatments,respectively.In comparison with RET treatment,the average values of the SPR under REM treatment were 10.9%and 8.9%higher in 45-60 cm and 60-80 cm soil depths,respectively.The average values of the SPR under PT treatment were 12.4%and 14.1%lower in 0-15 cm soil depth,and 23.9%and 10.4%lower in 15-30 cm soil depth than those under NT and RT treatments.However,the average value of the SPR under PT treatment was 11.2%and 22.0%higher in 60-80 cm soil depth than those under NT and RT treatments,respectively.The SPR generally decreased with the slope position declined in the deeper soil depth(except for the NT+RET treatment).The findings from this research can provide a scientific reference for the establishment of rational cultivation and the sustainable development of productivity on the sloping land of Mollisols in cold regions.

Soil surface roughness change and its effect on runoff and erosion on the Loess Plateau of China

As an important parameter in the soil erosion model, soil surface roughness（SSR） is used to quantitatively describe the micro-relief on agricultural land. SSR has been extensively studied both experimentally and theoretically; however, no studies have focused on understanding SSR on the Loess Plateau of China. This study investigated changes in SSR for three different tillage practices on the Loess Plateau of China and the effects of SSR on runoff and erosion yield during simulated rainfall. The tillage practices used were zero tillage（ZT）, shallow hoeing（SH） and contour ploughing（CP）. Two rainfall intensities were applied, and three stages of water erosion processes（splash erosion（I）, sheet erosion（II） and rill erosion（III）） were analyzed for each rainfall intensity. The chain method was used to measure changes in SSR both initially and after each stage of rainfall. A splash board was used to measure the splash erosion at stage I. Runoff and sediment data were collected continuously at 2-min intervals during rainfall erosion stages II and III. We found that SSR of the tilled surfaces ranged from 1.0% to 21.9% under the three tillage practices, and the order of the initial SSR for the three treatments was ZT〈SH〈CP. For the ZT treatment, SSR increased slightly from stage I to III, whereas for the SH and CP treatments, SSR decreased by 44.5% and 61.5% after the three water erosion stages, respectively, and the greatest reduction in SSR occurred in stage I. Regression analysis showed that the changes in SSR with increasing cumulative rainfall could be described by a power function（R2〉0.49） for the ZT, SH and CP treatments. The runoff initiation time was longer in the SH and CP treatments than in the ZT treatment. There were no significant differences in the total runoff yields among the ZT, SH and CP treatments. Sediment loss was significantly smaller（P〈0.05） in the SH and CP treatments than in the ZT treatment.

Application of fractal theory in assessing soil aggregates in Indian tropical ecosystems

Soil aggregation varies according to climatic and manage- ment factors, and is difficult to measure because of irregular shapes and sizes of soil aggregates. We applied fractal theory to assess soil aggrega- tion as affected by （1） land use change from forest to savanna, （2） nutri- ent additions in forest, ecotone, and savanna ecosystems, and （3） tillage practice and residue treatments in an agro-ecosystem. We used fractal dimensions nonlinear （D,o,-lin） and linear （Dlin） based on number of ag- gregates （N） and mass of aggregates （M） （the range of values were 2.6-2.89 and 2.694.41, respectively） to capture the variations in the sizes of soil aggregates due to land use and treatments/management in these ecosystems. The variation in the values of non-linear fractal dimension based on mass （DMnon-lin） was smaller in forest and savanna ecosystems with and without nutrient additions, while the variation was wider in agro-ecosystems with different management practices. Linear fractal dimensions based on number （Dr^i,） and mass （DMlin） of aggregates var- ied marginally in these ecosystems and did not capture the variations in soil aggregates well. The variations in non-linear fractal dimension indi- cate that continued nitrogen loading in forest accelerates the formation of macro-aggregates, whereas in savanna the situation was reversed. The values of non-linear fractal dimensions did not show significant change after 6 years of nutrient additions in the ecotone; reflecting a buffering mechanism of this system in soil aggregate formation. On the basis of non-linear fractal dimension values, we conclude that residue retention and minimum tillage are appropriate for proper maintenance of soil ag- gregate stability for sustained crop production in the Indian dry land agro-ecosystems

Relationship between soil surface roughness and hydraulic roughness coefficient on sloping farmland

The soil surface roughness and hydraulic roughness coefficient are important hydraulic resistance characteristic parameters. Precisely estimating the hydraulic roughness coefficient is important to understanding mechanisms of overland flow. Four tillage practices, including cropland raking, artificial hoeing, artificial digging, and straight slopes, were considered based on the local agricultural conditions to simulate different values of soil surface roughness in the Loess Plateau. The objective of this study was to investigate the relationship between the soil surface roughness and hydraulic roughness coefficient on sloping farmland using artificial rainfall simulation. On a slope with a gradient of 10°, a significant logarithmic function was developed between the soil surface roughness and Manning＇s roughness coefficient, and an exponential function was derived to describe the relationship between the soil surface roughness and Reynolds number. On the slope with a gradient of 15°, a significant power function was developed to reflect the relationship between the soil surface roughness and Manning＇s roughness coefficient, and a linear function was derived to relate the soil surface roughness to the Reynolds number. These findings can provide alternative ways to estimate the hydraulic roughness coefficient for different types of soil surface roughness.

No tillage outperforms conventional tillage under arid conditions and following fertilization

Reduced tillage practices present a tool that could sustainably intensify agriculture.The existing literature,however,lacks a consensus on how and when reduced tillage practices should get implemented.We reanalyzed here an extensive dataset comparing how regular tillage practices(i.e.,conventional tillage)impacted yield of eight crops compared to stopping tillage altogether(i.e.,no-tillage practice).We observed that aridity and fertilization favored no tillage over conventional tillage whereas conventional tillage performed better under high fertility settings.We further show that the responses are consistent across the crops.Our reanalysis complements the original and fills a gap in the literature questioning the conditions under which reducing tillage presents a viable alternative to common tillage practices.

Weed Management in Rainfed Upland Rice Fields under Varied Agro-Ecologies in Nigeria

The demand for rice to meet the dietary need in low-income countries is expected to witness an exponential rise as the population increases.Meeting the rice demand domestically has remained challenging due to significant yield loss caused by several biotic and abiotic factors.Among these factors,one of the most important is the high weed pressure that ravages the upland rice ecology.In Nigeria,several independent weed control techniques,such as physical,chemical and cultural methods,have been recommended and adopted for weed control across varying rice upland ecologies.However,outcomes of these approaches when used independently have not consistently led to an increase in yield.There remains an outstanding deficit between the actual yield and the potential rice yield.This review aimed to identify potential research gaps,and quest effective and sustainable weed management strategies in smallholder upland rice farming systems in Nigeria.A critical analysis of studies suggests the potential of sustainable weed management practices if adopted and adapted smartly in different upland ecologies in Nigeria.Competitiveness of upland rice against weeds can be enhanced through strategic integration of weed competitive cultivars,optimum nitrogen application timings(within weed-free periods),uniform plant spacing,and high seeding rates,with conventional herbicide/manual weed control practices.However,such management practices can only be engaged where inputs are supplied on time and the technical know-how is extended to farmers.The review equally highlights potential research gaps for further studies.

Changes in soil biochemical indicators at different wheat growth stages under conservation-based sustainable intensification of rice-wheat system

Soil microbes play critical roles in soil biogeochemistry, soil biological health and crop productivity. The current study evaluated the effects of tillage and residue management on changes in soil biochemical indicators at different growth stages of wheat after 5 years of rice-wheat system. Nine treatment combinations of tillage, crop establishment and crop residue management included three main plot treatments applied to rice:(1) conventional till direct dry seeded rice(CTDSR),(2) zero till direct dry seeded rice(ZTDSR), and(3) conventional puddled manual transplanted rice(CTPTR) and three subplot treatments in subsequent wheat:(1) conventional tillage with rice residue removed(CTW-R),(2) zero tillage with rice residue removed(ZTW-R) and(3) zero tillage with rice residue retained as surface mulch(ZTW+R). Irrespective of rice treatments, ZTW+R treatment had higher soil biochemical indicators compared with ZTW-R and CTW-R at all the growth stages of wheat. Generally, all the biochemical indicators were the highest at the flowering stage of wheat. Residual effect of rice treatments was also significant on biochemical quotients in wheat, which were the highest under ZTDSR followed by CTDSR and CTPTR. The present study provided three sensitive and reliable biochemical indicators(microbial biomass, basal soil respiration and microbial quotient) which respond rapidly to change in tillage and residue management practices in RWS of South Asia.

Carbon sequestration and emissions mitigation in paddy fields based on the DNDC model: A review

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.