Field Crops Research最新文献

Problem

Facing the multiple objectives of increasing production, carbon sequestration, and nitrogen reduction in farmland, optimizing straw and nitrogen fertilizer management to achieve a balance between grain production and ecological safety in the wheat-maize rotation system has become increasingly critical and urgent.

Methods

This study conducted a five-year field experiment in the Guanzhong Plain of China from 2017 to 2021 to investigate the effects and synergistic regulatory mechanisms of straw disposal methods (straw return, no-straw return) and nitrogen application rates (0, 150, 225, 300 kg ha⁻¹) during the maize season on soil greenhouse gas (GHG) emissions, crop yield, and soil organic carbon (SOC) and soil toatl nitrogen (STN) content.

Results

The results showed that under the scenario of no-straw return, fertilization increased soil nitrous oxide (N₂O) emissions by 35.9–64.0 %, and annual total crop yield by 16.4–22.8 %; however, under the straw return scenario, the increase in soil N₂O emissions due to fertilization decreased to 26.7–62.0 %, while the yield increase rose to 19.5–25.9 %. The interaction effect between straw return and nitrogen application was significant, with straw return boosting the contribution rate of nitrogen application to yield (2.2–4.4 %) and simultaneously reducing the contribution rate of nitrogen application to N₂O emissions (3.0–27.5 %). The study also indicated that the yield-increasing effect of straw return continued to increase with the duration of straw return, with the contribution rate to yield reaching 9.9 % after three years of continuous straw return, while the contribution rate of nitrogen application to yield increased by an average of 3.0 % per year. This suggests that there is significant potential for coupling straw return with reduced nitrogen application. Straw return combined with nitrogen fertilizer increased SOC content by 7.9–40.1 % and 3.7–12.5 %, STN content by 1.0–22.8 % and 6.1–13.9 %, respectively, compared to sole nitrogen application and sole straw return. Pathway analysis indicated that straw return combined with nitrogen fertilizer mainly enhanced soil carbon-nitrogen sequestration, improved fertilizer utilization efficiency and crop nutrition levels, reduced net global warming potential (GWP) and greenhouse gas intensity (GHGI), and synergistically regulated to increase yield while reducing GHG emissions.

Conclusion

The study highlights that straw return lowers the threshold for nitrogen application levels, suggesting that regulating nitrogen application levels between 224 and 256 kg ha⁻¹ during the maize season, and maintaining a nitrogen application level of 195 kg ha⁻¹ during the wheat season, is beneficial for long-term stable production and emission reduction in the wheat-maize rotation system farmland.

Context

Upland-paddy rotation can improve multiple-cropping index and crop yields; however, the mechanisms underlying the effects of dry-season crop diversification on rice yields and greenhouse gas (GHG) emissions under multiple rotation systems remain unclear.

Objective

Here, we aimed to clarify the intrinsic mechanisms whereby rice yields and GHG emissions respond to the diversification of dry-season crops and lay a theoretical foundation for developing agronomic measures that can stabilize yields and reduce GHG emissions.

Methods

Using a positioning experimental site for upland-paddy rotation, we measured rice-season CH₄ and N₂O emissions, crop yields, GHG-emission intensity (GHGI) levels, soil physical and chemical properties in garlic–rice (GR), wheat–rice (WR) systems for 3 years (2019–2020, and 2022), and in a rapeseed–rice (RR) system for 1 year (2022). The soil microbial dynamics of the three systems were only tested in 2022.

Results

The WR system had the highest CO₂ emission equivalent (CO₂-eq), with a 3-year interval value of 1898.24–16794.30 kg·ha⁻¹, the lowest yield (8490.10–9773.46 kg·ha⁻¹), and the highest GHGI (0.22–1.83). The GR system had the highest rice yield (9718.91–10769.75 kg ha⁻¹), a lower CO₂-eq (1588.55–12567.51 kg·ha⁻¹), and therefore a lower GHGI (0.16–1.24). The RR system had the lowest GHGI in 2022 (benefiting from the lowest CO₂-eq) and a slightly higher yield than that of the WR system. CH₄ contributed to >88 % of the CO₂-eq under the three systems in 2020 and 2022. The higher soil C:N ratio of the WR system stimulated methanogenic microorganisms, coupled with higher microbial biomass C levels, and ultimately increased CH₄ emissions substantially. The soil C:N ratios of the GR and RR systems were significantly lower than that of the WR system because the soil total nitrogen (TN) of both systems was higher and increased CH₄ emissions were avoided. The higher levels of N nutrients (TN, NO₃^--N, and NH₄⁺-N) in the GR and RR systems also enhanced rice yields, with respective increases of 10.37 % and 1.22 %, compared with that of the WR system.

Conclusions

The diversified cultivation of dry-season crops in upland-paddy rotation systems affected rice yields and GHG emissions by changing the ratios of C and N.

Implications

Our findings highlight the importance of future research involving comprehensive agronomic measures to help reduce emissions, including fertilizer management, straw management, and tillage methods.

Context

Straw return under rotary tillage has been used for two decades in the rice-rotated wheat cropping system in the lower Yangtze region of China, but it has become prone to reduce wheat emergence and yield in recent years, and alternative tillage methods are required to ensure the high wheat yields.

Aims

To determine whether straw return under deep tillage can improve wheat yield and under what mechanisms. We hypothesize that straw return under deep tillage can increase wheat seedling number by reducing rice stubble and straw coverage, and expand the nutrient pool and root system of the plow soil profile to keep post-anthesis viability for increasing wheat yield.

Methods

A field study was conducted during two consecutive years and included four treatments: rotary tillage after straw removal (RT); rotary tillage after straw return (RTS); shallow rotary tillage followed by straw mulch (STS) and deep tillage after straw return (DTS). Wheat seedling number, yield, aboveground nutrient uptake, growth period, root characteristics, and soil nutrients were measured.

Results

Compared to RT, seedling number under RTS and STS decreased by 8.3 % and 13.4 %, respectively, while DTS increased by 14.7 %. Wheat yield under RTS and STS decreased by 3.0 % and 7.3 %, respectively, while DTS increased by 8.2 %. The reduction in seedling number under RTS and STS would be partially offset in wheat yield by an increase in effective tiller number per plant and grain weight. Consequently, the variation in wheat yield among treatments was less than the variation in seedling number. Aboveground N and P accumulation in wheat under DTS were higher than the other treatments. Among four treatments, DTS had the highest root distribution and soil N and P contents in the middle and deep soil layers, thus prolonged grain filling duration. Wheat nutrient uptake at maturity and yield were significantly correlated with root weight density and root length density in both middle and deep soil layers.

Conclusions

Straw return under deep tillage can increase nutrient supply capacity and root distribution in deep soil while ensuring wheat emergence, enabling better filling of post-anthesis wheat and yield. It is therefore an effective alternative tillage method suitable for the rice-rotated wheat cropping system.

Topping and planting density are key agronomic management practices to optimize cotton plant structure for machine harvesting and light capture. However, modelling the effects of these practices on canopy light utilization in the field, in order to improve cotton management, remains challenging. Functional-structural plant modelling is a computational approach to explore the effects of agronomic practices on shaping plant architecture and thus light interception. This study, for the first time, utilizes the CottonXL model to quantify the significant impact of chemical topping compared to manual topping on radiation interception on machine-harvested cotton in China at different planting densities, providing new management strategies for cotton production. A more compact plant structure is shaped by chemical topping through inhibiting leaf expansion and shortening internodes of both the main stem and fruiting branches, thereby allowing more PAR interception by middle and lower leaves. Simulation results showed that the total PAR intercepted by the canopy over entire growth season was increased by 11.3 % under chemical topping compared to manual topping. This positive effect became even more pronounced with increasing plant density. These results indicate that chemical topping could be beneficial for optimizing canopy structure, enhancing light interception and lint yield, especially at higher plant densities. The results illustrate the importance of shaping plant structure for improving radiation resource capture and exemplify the potential of optimizing topping strategy and plant density to enhance crop performance. They also demonstrate the utility of a functional-structural plant model for guiding crop management.

Current cultivation practices for field transplanted potato crops grown from nursery-raised hybrid potato seedlings are mostly borrowed from the tuber-based conventional system. Most studies on field performance of field transplanted seedling crops have largely reported the use of ridged rows and in exceptional cases, the use of beds. It is therefore critical to assess the feasibility of the use of alternative ridge or bed systems for cultivation of field-transplanted nursery-raised potato seedlings considering the differences in physiological behaviour of crops grown from different starting materials. This study assessed the effects of six systems which included bed and ridge systems of different dimensions and planting configurations for field transplanted seedling crops. Field crop establishment, canopy growth and development as well as yield and yield components were assessed. In general, systems that boasted high plant densities resulted in faster canopy development and higher number of tubers and tuber yield. Bed systems (raised and flat beds; 8.0 plants m⁻²) therefore gave the highest numbers of tubers and tuber yield across all treatments. These systems also produced the most tubers in all tuber size classes resulting in the highest yields in all classes. Standard ridge systems (full- and half ridges; 0.75 m row distance), had the lowest plant populations (5.3 plants m⁻²) which resulted almost always in fewer tubers and lower yield. Other ridge systems (0.9-m and 0.5-m ridge systems), although having higher plant densities than the standard ridge systems (8.9 and 8.0 plants m⁻², respectively) still performed poorer than the bed systems. The small and compact ridges in the 0.5-m ridge system and the compact arrangement of plants in the 0.9-m ridge system caused these effects. Conclusively, based on this study, productivity in field transplanting systems is highly influenced by plant density. Further, cultivation systems boasting higher planting densities should be recommended when the goal for production is to produce large quantities of seed tubers (> 35; ≤ 50 mm).

Context

Potato is one of the staple food crops in China. Optimized agronomic management could enhance potato yield, while the economic benefits of farmers depend on both the yield and marketable tuber rate (MTR) of potato. The key meteorological factors to the variation of MTR of potato and the relationship between potato yield and MTR remain unclear.

Objective

The study aims to explore the key meteorological factors to the variation of MTR of potato and the relationship between potato yield and MTR.

Methods

A 5-year (20172021) rainfed field experiment with 3-planting date and 3-cultivar maturity of potato was conducted to investigate the optimum combination of planting date and cultivar maturity for both high yield and MTR under different year types and the relationship between potato yield and MTR. The meteorological factors during three growth stages including planting to 10 d before the tuberization, the tuber formation period (10 d before the tuberization to 10 d after the tuber bulking), 10 d after the tuber bulking to maturity were used to identify the key meteorological factors to yield and MTR of potato.

Results

Throughout the experimental period, there were large variations in the fresh tuber yield and MTR of potato ranging between 4.827 t ha⁻¹ and 061 %, respectively. Early- to middle planting of middle maturing cultivars under warm-wet years resulted in higher MTR, yield, and economic benefit compared to other combinations. Under warm-dry years, while early planting of early- to middle-maturing cultivars could achieve higher yield and MTR, farmers still suffer economic losses under most combinations of planting date and cultivar maturity. On the whole, there was a synergistical enhancement between yield and MTR of potato (R²=0.86, P<0.01). The precipitation and growing degree day (GDD) during tuber formation period (TF), precipitation before TF, and the interaction of precipitation and mean air temperature after TF could account for 77 % of the variations in total tuber yield while marketable tuber rate could be determined by the precipitation from planting to 10 d after the tuber bulking, the HDD during TF, and the interaction of precipitation and mean air temperature before TF (R²=0.79).

Conclusions:

Total tuber yield and MTR of potato could be synergistically enhanced by optimizing planting date and cultivar maturity. Compared with total tuber yield, MTR influences economic benefit of potato more significantly.

Implications:

These findings could serve as a valuable reference for determining the optimal planting date and cultivar maturity of potato under different hydrothermal year types to enhance the MTR, yield, and economic benefit of rainfed potato planting and provide an important implication on potato model improvement.

Context

Global warming's escalating severity necessitates sophisticated approaches for predicting rice yield.

Research Question

Combining crop models with data-driven techniques, such as machine learning, can more effectively grasp the complex interplay of variables influencing crop growth. It remains a significant challenge to balance accuracy and interpretability in such hybrid models.

Methods

The research integrated the Decision Support System for Agrotechnology Transfer (DSSAT) with statistical and machine learning models respectively, to assess rice yield changes in China under four future Shared Socio-economic Pathway (SSP). SSPs are scenarios that integrate socioeconomic trends with greenhouse gas emissions and radiative forcing pathways, which affect the phenology and yield of rice. The Shapley Additive Explanation (SHAP) method was employed to interpret the model, effectively determining the interplay among variables influenced rice yields. Mitigated the negative impacts of climate change on rice yield through the planting date optimization.

Results

Projections indicate significant rice yield losses in China without CO₂, worsening with increased radiative forcing (p < 0.001). Considering rising CO₂, single-season rice yields are projected to increase by 0.1–3.6 %, early rice by 4.6–9.5 %, while late rice yields are still decrease by 2.3–8.8 %. The rising CO₂ can offset yield losses for single and early rice but not for late rice. The hybrid approach which combined the Random Forest (RF) with the DSSAT performed best in predicting rice yield. Studies showed that rising temperatures caused rice yield losses in China, yet we found that Growing Degree Days (GDD) exerted a more negative impact (p < 0.001). In high-precipitation regions, deep soil moisture is more influential than shallow soil moisture, whereas the reverse was true in drier areas (p < 0.001). Advancing planting dates for early and single rice and delaying for late rice can increase yields (p < 0.001). Adjusting to optimal planting dates, single-season rice yields increased by 3.3–6.3 %, early rice increased by 9.7–18.3 %, while late rice still decreased by 1.0–4.7 %.

Conclusions

Without considering the impact of CO₂, significant rice yield losses in China are projected. Even with the fertilization effect of CO₂, rice yields remain negatively impacted by climate change. However, implementing appropriate measures, such as optimizing planting dates, can help Chinese rice production benefit under changing climate.

Implications

This study offers insights into balancing accuracy and interpretability in hybrid models and provides guidance for local policymakers to address future climate change.

Context

Sugar production in China is struggling to keep up with the increasing demand driven by rapid growth in sugar consumption. However, knowledge gap persists in terms of how to locate and concentrate the sugarcane production in advantageous areas to secure the production of high-quality sugarcane characterized by high sugar content, while also optimizing resource utilization.

Objective

The objective of the study was to explore the effects of environmental and management factors on sugarcane yield and quality (characterized by sugar content). Moreover, it sought to determine how China's future sugarcane needs could be met with fewer resource inputs through production optimization.

Methods

This study conducted a comprehensive search and compiled 411 groups of measured data from 64 peer-reviewed publications on sugarcane production in China. Additionally, a Random Forest model was developed based on trial data and farmer survey data to predict county-level sugarcane yield and quality in China. Taking into consideration China's projected sugarcane demand in 2030, this study proposed three sugarcane planting scenarios to explore potential pathways for future sugarcane production. These scenarios included: S0, where all sugarcane acreages maintain their current level of production; S1, where medium- and low-yield (or quality) fields transition into high- and medium-yield (or quality) fields; and S2, where all sugarcane acreages strive for both high yield and high quality.

Results

Results showed that overall field management could improve yield by 37.1 % and quality by 5.26 %. Soil organic matter (SOM), available phosphorus (AP), mean annual precipitation (MAP), and soil clay are the most important drivers of yield. pH, AP, total nitrogen (TN), and SOM are the most important drivers of quality. S2 scenario reduced land inputs by 11 %, nutrient inputs by 5 %, and irrigation inputs by 13 %, based on meeting future sugarcane demand in 2030.

Conclusions

By identifying and focusing on dominant planting areas, we can enhance the quality and efficiency of sugarcane cultivation as a response to China's future demand for sugarcane. This approach will not only meet future demands for sugarcane but also alleviate the dual pressures of limited resources and environmental concerns.

Significance

Our research provides a conceptual framework to enable China to meet its future sugar demand and consumption more efficiently and in an environmentally friendly manner, thereby conserving resources and reducing environmental impact.

Context

Alternating wetting and drying (AWD) is an irrigation practice, alternative to continuous flooding, to improve the agro-environmental sustainability of rice cultivation. Benefits include reduction in water consumption, methane (CH₄) emissions and arsenic (As) concentrations in grain. However, drainage periods during AWD can negatively affect nitrogen (N) use efficiency by the crop and grain yields, while increasing nitrous oxide (N₂O) emissions and cadmium (Cd) contents in grain.

Objective

The objective of this study was to provide a holistic evaluation of AWD adoption in temperate rice cropping systems, including associated trade-offs. We hypothesized that the adoption of AWD in water seeded rice paddies can reduce the global warming potential (GWP) without affecting plant N uptake or introducing yield gaps, and also maintain a high quality of rice grain by limiting the uptake of metal(loid)s present in the soil, thereby resulting in an overall positive agro-environmental performance.

Methods

In a two-year field experiment in NW Italy two alternative irrigation practices involving water seeding followed by AWD management of different severity (AWD_safe and AWD_strong) were evaluated relative to the conventional water seeding and continuous flooding (WFL), comparing three different rice varieties. Yields and yield components, plant N uptake, apparent N recovery (ANR), metal(loid) concentrations in grain, and CH₄ and N₂O emissions were evaluated.

Results

AWD_safe and AWD_strong maintained or increased yields compared to WFL depending on varieties, despite an increase in sterility. There were no consistent differences in N uptake and ANR. Both AWD_safe and AWD_strong significantly reduce As concentration in grain, but significantly increase Cd and nickel (Ni). AWD_safe and AWD_strong reduced CH₄ emissions by 45–55 % and 40–73 %, respectively, compared toWFL, while no increase in N₂O emissions was observed. This resulted in a reduction in the GWP of 46 and 54 % with AWD_safe and AWD_strong, respectively.

Conclusions and Implications

AWD was shown to be effective for mitigating GHG emissions from temperate rice cropping systems while maintaining high yield performance comparable or higher than WFL. AWD may represent a viable alternative to continuous flooding to improve agro-environmental sustainability of temperate rice cropping systems, but the trade-off between decreasing As and increasing Cd and Ni contents in the grain may represent an important concern for food safety with the adoption of this alternative water management practice.