Optimization and Experiment of Straw Back-Throwing Device of No-Tillage Drill Using Multi-Objective QPSO Algorithm

Reducing operation energy consumption is the development demand of conservation tillage equipment. In order to solve the problems of high power consumption and the easy blockage of the no-tillage drill under full straw retention, the key parameters of the straw back-throwing device were optimized in this study. The Box–Behnken central combination test method was used to analyze the influence of the impeller rotating speed, feed quantity and cross-sectional area of the throwing pipe on the specific power consumption and throwing speed, the mathematical models of which were built with the aid of the least square method. In addition, the mathematical models were optimized by using a multi-objective quantum behaved particle swarm optimization (QPSO) with an improved target weighting coefficient. The optimization results indicated that, when the impeller rotating speed was 2287 r/min, the feed quantity was 1.1 kg/s and the cross-sectional area of the throwing pipe was 506.997 cm2, the specific power consumption and throwing speed by the models were 7528 m2/s2 and 11.73 m/s, respectively. The models were verified by comparing the optimization results with the measured data in the simulation filed tests, which proved that the multi-objective QPSO algorithm was feasible to optimize the working and structural parameters of the straw back-throwing device of the no-tillage drill under full straw retention. The results provide references for the parameter optimization of similar no-tillage drills under straw retention.

Impact of multiple soil conservation practices on rice yields and chemical fertiliser use in China

PurposeThis paper analysed survey data of 715 rice-producing households in China to assess the determinants of adoption of five mutually exclusive soil conservation practices (SCPs) and their impact on rice yield and chemical fertiliser use.Design/methodology/approachThe multinomial endogenous treatment effects model was used to account for selection bias and endogeneity arising from both observed and unobserved heterogeneity.FindingsFarms that adopted SCPs as a package experienced an increase in rice yield and decrease in chemical fertiliser use. Adoption of SCPs as a package led to a 12.0% increase in yield and 15.2% decrease in chemical fertiliser use; these results have policy implications for the non-point source pollution control in the agricultural sector. In contrast, adoption of straw retention only significantly reduced yield by 4.9% and increased chemical fertiliser use by 18.1%.Originality/valueThe authors evaluate and compare multi-type of SCPs, such as straw retention, deep tillage and use of organic fertiliser, separately or in combination, and their impacts on smallholder farmers’ rice yield and chemical fertiliser usage.

Effect of straw retention on carbon footprint under different cropping sequences in Northeast China

Inappropriate farm management practices can lead to increased agricultural inputs and changes in atmospheric greenhouse gas (GHG) emissions, impacting climate change. This study was initiated in 2012 to assess the potential for straw retention to mitigate the negative environmental impact of various cropping systems on the Songnen Plain using the life cycle assessment (LCA) method combined with field survey data. Straw retention (STR) and straw removal (STM) treatments were established in continuous corn (CC) and corn-soybean rotation (CS) systems in a split-plot experiment. The effects of straw retention on the carbon footprint (CF) of cropland under different cropping systems were compared. The CF under CC was 2434–2707 kg CO2 ha−1 year−1, 49–57% higher than that under CS. Nitrogen fertilizer produced the most CO2, accounting for 66–80% of the CF. The carbon balances of the CC and CS systems with STR were positive, with annual carbon sequestrations of 9633 and 2716 kg CO2 ha−1 year−1, respectively. The carbon balance (CB) of CC-STR was 255% higher than that of CS-STR. This study demonstrates that STR under CC cultivation is an environmentally friendly practice for agricultural production, can help achieve high-yield and low-carbon production in rainfed cropland, and can support the sustainable development of grain production in Northeast China.

Effect of straw retention on carbon footprint under different cropping sequences in Northeast China

Inappropriate farm management practices can lead to increased agricultural inputs and changes in atmospheric greenhouse gas (GHG) emissions, impacting climate change. This study assessed the potential of straw retention to mitigate the negative environmental impact of different cropping systems on the Songnen Plain using the life cycle assessment (LCA) method combined with field survey data. Straw retention (STR) and straw removal (STM) treatments were established in continuous corn (CC) and corn-soybean rotation (CS) systems in a split-plot experiment. The effects of straw retention on the carbon footprint (CF) of cropland under different cropping systems were compared. The CF under CC was 2434.0–2706.9 kg CO 2 ha -1 yr -1 , 49.3%–57.3% higher than that under CS. Nitrogen fertilizer produced the most CO 2 , accounting for 66.2%-80.4% of the CF. The carbon balances of the CC and CS systems with STR were positive, with annual carbon sequestrations of 9632.5 and 2715.9 kg CO 2 ha -1 yr -1 , respectively. The carbon balances of the CC and CS systems with STM was negative, with annual carbon sequestrations of -3589.2 and -3006.2 kg CO 2 ha -1 yr -1 , respectively. This study demonstrates that STR under CC cultivation is an environmentally friendly practice for agricultural production, can help achieve high-yield and low-carbon production in rainfed cropland, and can support the sustainable development of grain production in Northeast China.

Comparison of carbon footprint and net ecosystem carbon budget under organic material retention combined with reduced mineral fertilizer

Background Excessive application of chemical fertilizer has resulted in lower nitrogen uptake and utilization efficiency of crops, decreasing soil fertility, increasing greenhouse gas emissions, and worse environmental pollution. Organic material retention is regard as the key to solve these problems. The objective of this study is to conduct an assessment of carbon budget under Astragalus sinicus L. and rice straw retention combined with reduced mineral fertilizer based on the 2-year field experiment in a paddy field in the south of China. The experiment was randomized complete block design including four treatments with triplicates: control CK (winter follow, 120 kg ha−1 N fertilizer for each rice season) and three treatments with Astragalus sinicus L. and rice straw retention named RA, RB, and RC (reduced N fertilizer by 15%, 27.5%, and 40% in each rice season). Results Treatments RA, RB, and RC increased greenhouse gas emissions by 9.30–101.25%, among which CH4 accounted for more than 60%; Carbon input of crops from treatments RA, RB, and RC increased by 2.25–12.10% compared with control CK over the 2 years. Though treatments RA, RB, and RC enhanced CO2 emissions, treatment RB decreased carbon footprint and became carbon sink. Conclusions The results of this study reveal that treatment RB (Astragalus sinicus L. and rice straw retention with reduced N fertilizer by 27.5%) is better in reducing chemical fertilizer amount, increasing crop yield and carbon input, which is more conductive to sustainable development of agriculture.

Straw retention efficiently improves fungal communities and functions in the fallow ecosystem

Background Straw retention is a substitute for chemical fertilizers, which effectively maintain organic matter and improve microbial communities on agricultural land. The purpose of this study was to provide sufficient information on soil fungal community networks and their functions in response to straw retention. Hence, we used quantitative real-time PCR (qRT-PCR), Illumina MiSeq (ITS rRNA) and FUNGuild to examine ITS rRNA gene populations, soil fungal succession and their functions under control (CK) and sugarcane straw retention (SR) treatments at different soil layers (0–10, 10–20, 20–30, and 30–40 cm) in fallow fields. Result The result showed that SR significantly enhanced ITS rRNA gene copy number and Shannon index at 0–10 cm soil depth. Fungi abundance, OTUs number and ACE index decreased with the increasing soil depth. The ANOSIM analysis revealed that the fungal community of SR significantly differed from that of CK. Similarly, significant difference was also observed between topsoil (0–20 cm) and subsoil (20–40 cm). Compared with CK, SR decreased the relative abundance of the pathogen, while increased the proportion of saprotroph. Regarding soil depth, pathogen relative abundance in topsoil was lower than that in subsoil. Besides, both sugarcane straw retention and soil depths (topsoil and subsoil) significantly altered the co-occurrence patterns and fungal keystone taxa closely related to straw decomposition. Furthermore, both SR and topsoil had higher average clustering coefficients (aveCC), negative edges and varied modularity. Conclusions Overall, straw retention improved α-diversity, network structure and fungal community, while reduced soil pathogenic microbes across the entire soil profile. Thus, retaining straw to improve fungal composition, community stability and their functions, in addition to reducing soil-borne pathogens, can be an essential agronomic practice in developing a sustainable agricultural system.

Comparison of carbon footprint and net ecosystem carbon budget under organic materials retention combined with reduced mineral fertilizer

Background: Excessive application of chemical fertilizer has resulted in lower nitrogen uptake and utilization efficiency of crops, decreasing soil fertility, increasing greenhouse gas emissions, and worse environment pollution. Organic material retention is regard as the key to solve these problems. he objective of this study is to conduct an assessment of carbon budget under Astragalus sinicus L. and rice straw retention combined with reduced mineral fertilizer based on the two-year field experiment in a paddy field in the south of China. The experiment was randomized complete block design including four treatments with triplicates: control CK (winter follow, 120 kg ha-1 N fertilizer for each rice season) and three treatments with Astragalus sinicus L. and rice straw retention named RA, RB, and RC (reduced N fertilizer by 15%, 27.5%, and 40% in each rice season). Results: Treatments RA, RB, and RC increased greenhouse gases emissions by 9.30%~101.25%, among which CH4 accounted for more than 60%; Carbon input of crops from treatments RA, RB, and RC increased by 2.25%~12.10% compared with control CK over the two years. Though treatments RA, RB, and RC enhanced CO2 emissions, however, treatment RB decreased carbon footprint and became carbon sink.Conclusions: The results of this study reveal that treatment RB (Astragalus sinicus L. and rice straw retention with reduced N fertilizer by 27.5%) is better in reducing chemical fertilizer amount, increasing crop yield and carbon input, which is more conductive to sustainable development of agriculture.