Response of soil CO2 emissions and water-carbon use efficiency of winter wheat to different straw returning methods and irrigation scenarios.

BACKGROUND: The shortage of water resources and the increase of greenhouse gas emissions from soil seriously restrict the sustainable development of agriculture. Under the premise of ensuring a stable yield of winter wheat through a reasonable irrigation scenario, identifying a suitable straw returning method will have a positive effect on agricultural carbon sequestration and emission reduction in North China Plain. RESULTS: Straw burying (SR) and straw mulching (SM) were adopted based on traditional tillage under in the winter wheat growing season of 2020-2021 and 2021-2022. Three irrigation scenarios were used for each straw returning method: no irrigation (I0), irrigation 60 mm at jointing stage (I1), and irrigation of 60 mm each at the jointing and heading stages (I2). Soil moisture, soil respiration rate, cumulative soil CO2 emissions, yield, water use efficiency (WUE) and soil CO2 emission efficiency (CEE) were mainly studied. The results showed that, compared to SM, SR improved the utilization of soil water and enhanced soil carbon sequestration. SR reduced soil respiration rate and cumulative soil CO2 emissions in two winter wheat growing seasons, and increased yield by increasing spike numbers. In addition, with an increase in the amount of irrigation, soil CO2 emissions and yield increased. Under SR-I1 treatment, WUE and CEE were the highest. SR-I1 increases crop yields at the same time as reducing soil CO2 emissions. CONCLUSION: The combination of SR and irrigation 60 mm at jointing stage is a suitable straw returning irrigation scenario, which can improve water use and reduce soil CO2 emission in NCP. © 2023 Society of Chemical Industry.

Delayed irrigation at the jointing stage increased the post-flowering dry matter accumulation and water productivity of winter wheat under wide-precision planting pattern.

BACKGROUND: The North China Plain (NCP) faces a severe water shortage, and the amount of rainfall cannot guarantee the growth and development of winter wheat. Therefore, it is important to explore a suitable irrigation and planting pattern to solve the problem of water shortage in this region. RESULTS: A 4-year experiment was carried out in the NCP during 2015-2019. The main plots included two planting patterns: a wide-precision planting pattern (W) and a conventional planting pattern. Two irrigation regimes were established for each planting pattern: 60-mm irrigation at the jointing stage (I1) and 60-mm irrigation delayed 10 days at the jointing stage (I2). The soil water consumption, dry matter translocation, grain yield and crop water productivity were investigated. The results showed that WI2 treatment obtained the highest grain yield and crop water productivity. The wide-precision planting pattern could significantly decrease soil water consumption; however, delayed irrigation effectively reduced soil water consumption only in normal rainfall years. The coupling of delayed irrigation at the jointing stage and a wide-precision planting pattern significantly enhanced dry matter accumulation after flowering and the contribution of dry matter accumulation after flowering to grain yield during the growing seasons. WI2 could decrease the evapotranspiration and improve the grain yield, thus increasing crop water productivity. CONCLUSION: The combination of a wide-precision planting pattern and delayed irrigation at the jointing stage was the appropriate agronomic practice for efficient grain yield and crop water productivity in the North China Plain. © 2022 Society of Chemical Industry.

[Effects of brackish water irrigation on grain quality characteristics and yield of winter wheat]. / 咸水灌溉对冬小麦籽粒品质特性和产量的影响.

Brackish water resource is widely distributed in the North China Plain, which has not been effectively utilized. Using brackish water for irrigation can alleviate water resource conflict in the well-irrigated area and solve the problem of groundwater over-exploitation of the North China Plain. A long-term experiment (since 2006) was conducted to investigate the effects of brackish water irrigation on the quality and yield of winter wheat in the North China Plain. There were five salinity degrees of irrigation water, i.e. 1, 2, 4, 6, and 8 g·L-1, respectively. The results showed that higher salinity degree of irrigation water (4-8 g·L-1) significantly increased water absorption, development time, sedimentation, wet gluten content, and protein content, but decreased the stabilization time, flour yield, and gluten index. There was no significant difference between the treatments of 1 g·L-1 and 2 g·L-1 on grain yield and yield components, but the treatment of 2 g·L-1 significantly improved grain quality, including water absorption, development time, sedimentation, wet gluten, and protein content. Higher salinity degree of irrigation water (4-8 g·L-1) treatments significantly decreased spike number (44.0%-60.7%) and grain yield (35.6%-64.7%), compared with 1 g·L-1 treatment. Results of principal component analysis showed that 2 g·L-1 treatment had the best overall effect with no significant decrease in grain yield and quality of grain. This study could provide theoretical basis and technical support for use of brackish water in the North China Plain.

Effect of Long-Term Biodegradable Film Mulch on Soil Physicochemical and Microbial Properties.

Biodegradable mulches have become the focus of attention, as pollution caused by leftover plastic mulch material becomes increasingly severe. However, the impact of biodegradable mulches to the soil needs to be further investigated. An experiment was conducted to evaluate the impact of no-mulch, biodegradable film mulch (BM) and polyethylene film mulch (PM) on the soil's physical, chemical and biological properties after six years (2013-2019) of mulching in garlic growing season in a garlic-maize rotation. Results showed that the soil bulk density of the 10-20 cm soil layer under BM decreased by 12.09-17.17% compared with that under PM. The soil total nitrogen content increased significantly by 14.75-28.37%, and the soil available phosphorus and potassium content increased by 64.20% and 108.82%, respectively. In addition, BM increased the soil's microbial, soil urease, and soil catalase activities compared with those for PM. To sum up, BM can reduce soil bulk density, and long-term use of BM does not cause a decrease in soil nutrient content and microbial activity. On the contrary, it can improve soil quality. This study helps accumulate data for the environmental safety evaluation of BM and provides theoretical and technical support for the large-scale promotion of biodegradable mulches.

Carbon emission and water use efficiency response to tillage methods and planting patterns of winter wheat in the North China Plain.

BACKGROUND: Implementing sustainable farming practices for winter wheat (Triticum aestivum L.) in the North China Plain may be a way to reduce carbon emissions. No tillage generally results in less net CO2 loss from farmland, but no tillage also reduces the grain yield and water use efficiency (WUE) of winter wheat. Wide-precision planting of winter wheat may enhance the grain yield and WUE; however, it is not known precisely how tillage and planting patterns affect CO2 exchange, grain yield and WUE. METHODS: In this study, two tillage methods (conventional tillage, T and no tillage, NT) and two planting patterns (conventional planting, C and wide-precision planting, W) were used in two consecutive winter wheat growing seasons. RESULTS: Compared with the T treatments, the NT treatments had significantly lower cumulative net CO2 emissions in 2015-2016 and 2016-2017 (30.8 and 21.3%, respectively), and had lower grain yields (9.0 and 9.4%, respectively) and WUE (6.0 and 7.2%, respectively). The W treatments had a compensating effect on grain yield failure and reduced cumulative net CO2 emissions more than C treatments, thereby increasing WUE, reducing carbon emissions per unit water consumption, and increasing the yield carbon utilization efficiency (YCUE). The lowest cumulative CO2 emissions and highest YCUE were observed for NT with W treatment. Results from this analogous tillage experiment indicated that NT and W farming practices provide an option for reducing carbon emissions and enhancing WUE and YCUE for sustainable winter wheat development.

Response of water use efficiency and carbon emission to no-tillage and winter wheat genotypes in the North China Plain.

No-tillage management practices reduce net CO2 losses from farmland and keep soil from degrading, but also decrease winter wheat grain yield and water use efficiency (WUE) in the North China Plain (NCP). Suitable management practices, namely, the choice of genotypes, could enhance crop yield and WUE; however, how the WUE and CO2 exchange responds to no-tillage practices and winter wheat genotypes remains unclear. In the 2015-2016 and 2016-2017 winter wheat growing seasons in the NCP, a field experiment was carried out, and tested two tillage methods (no-tillage with mulching and conventional tillage) and two winter wheat genotypes ('Tainong 18' and 'Jimai 22'). The goal of the study was to identify the relationship between winter wheat grain yield, water consumption, and carbon emissions in no-tillage practices. The results showed that, compared to conventional tillage, no-tillage significantly reduced the net CO2-C cumulative emissions and water consumption; however, the grain yield was significantly reduced by 6.8% and 12.0% in the first and second growing seasons, respectively. Compared with Jimai 22, Tainong 18 had a compensatory effect on the yield reduction caused by no-tillage. As a result, the yield carbon utilization efficiency (R) and WUE were the highest in no-tillage with Tainong 18 (NT18), and the carbon emission per unit water consumption was the lowest in NT18. The results support the idea that a combination of no-tillage with genotype can improve the regulation of soil carbon emissions and water consumption of winter wheat, thus, providing theoretical support for sustainable crop production and soil development in the NCP.

Compensation effect of winter wheat grain yield reduction under straw mulching in wide-precision planting in the North China Plain.

Climate change and the growing demand for food security force growers to identify ways both to improve food production and to reduce agricultural carbon emissions. Although straw mulching is known to decrease CO2 emissions, winter wheat grain yield in the North China Plain was declined under straw mulching. In an effort to determine the most effective way to increase winter wheat yield under straw mulching, a field experiment was conducted using two planting patterns (wide-precision planting and conventional-cultivation planting) and two straw mulching rates (0 and 0.6 kg/m2). The results showed the wide-precision planting/non-mulching treatment significantly increased the leaf area index more than the other three treatments at the early growth stage. This treatment improved aboveground dry matter accumulation and was conducive to increased spike weight in the late growth stage. By contrast, straw mulching significantly reduced winter wheat grain yields by lowering both spike number and 1000-grain weight at the mature plant stage. In the wide-precision planting/mulching treatment, a significantly increased spike number compensated for grain yield losses. The results support the idea that wide-precision planting combined with straw mulching has the potential to decrease the winter wheat grain yield reduction previously observed with straw mulching in the North China Plain.

Responses of Winter Wheat Yield and Water Use Efficiency to Irrigation Frequency and Planting Pattern.

A suitable planting pattern and irrigation strategy are essential for optimizing winter wheat yield and water use efficiency (WUE). The study aimed to evaluate the impact of planting pattern and irrigation frequency on grain yield and WUE of winter wheat. During the 2013-2014 and 2014-2015 winter wheat growing seasons in the North China Plain, the effects of planting patterns and irrigation frequencies were determined on tiller number, grain yield, and WUE. The two planting patterns tested were wide-precision and conventional-cultivation. Each planting pattern had three irrigation regimes: irrigation (120 mm) at the jointing stage; irrigation (60 mm) at both the jointing and heading stages; and irrigation (40 mm) at the jointing, heading, and milking stages. In our study, tiller number was significantly higher in the wide-precision planting pattern than in the conventional-cultivation planting pattern. Additionally, the highest grain yields and WUE were observed when irrigation was applied at the jointing stage (120 mm) or at the jointing and heading stages (60 mm each) in the wide-precision planting pattern. These results could be attributed to higher tiller numbers as well as reduced water consumption due to reduced irrigation frequency. In both growing seasons, applying 60 mm of water at jointing and heading stages resulted in the highest grain yield among the treatments. Based on our results, for winter wheat production in semi-humid regions, we recommend a wide-precision planting pattern with irrigation (60 mm) at both the jointing and heading stages.

Response of soil CO2 emission and summer maize yield to plant density and straw mulching in the North China Plain.

Demand for food security and the current global warming situation make high and strict demands on the North China Plain for both food production and the inhibition of agricultural carbon emissions. To explore the most effective way to decrease soil CO2 emissions and maintain high grain yield, studies were conducted during the 2012 and 2013 summer maize growing seasons to assess the effects of wheat straw mulching on the soil CO2 emissions and grain yield of summer maize by adding 0 and 0.6 kg m(-2) to fields with plant densities of 100,000, 75,000, and 55,000 plants ha(-1). The study indicated that straw mulching had some positive effects on summer maize grain yield by improving the 1000-kernel weight. Meanwhile, straw mulching effectively controlled the soil respiration rate and cumulative CO2 emission flux, particularly in fields planted at a density of 75,000 plants ha(-1), which achieved maximum grain yield and minimum carbon emission per unit yield. In addition, soil microbial biomass and microbial activity were significantly higher in mulching treatments than in nonmulching treatments. Consequently, summer maize with straw mulching at 75,000 plants ha(-1) is an environmentally friendly option in the North China Plain.

[Effects of straw mulching and irrigation on solar energy utilization efficiency of winter wheat farmland].

The study showed that straw mulching decreased the basic seedlings and tillers of winter wheat and the leaf area index (LAI) at earlier growth stage, but increased the LAI at latter growth stage. Straw mulching and irrigation reduced the transmittance and reflectance of PAR, resulting in the increase of PAR capture ratio mainly at the height of 40-60 cm. The solar energy utilization ratio of grain was decreased by straw mulching, while that of stem and leaf was increased. The total solar energy utilization efficiency of winter wheat could also be increased by straw mulching.