| Drought and soil erosion are the main factors restricting food production and economic development in the semi-arid Loess Plateau of China.Affected by climate change and inappropriate human activities,the region suffers from water shortages,long duration of drought,low soil fertility,and food security risks.To resist climate change,humans adopt effective water-saving farming measures to improve crop productivity,achieve food safety production,and sustainable agricultural development.Ridge-furrow rainwater harvesting technology can effectively increase soil moisture,reduce ineffective evaporation of water,control soil erosion,and improve water resource utilization efficiency,and is an important water-saving farming measure to achieve stable and sustainable alfalfa（Medicago sativa L.）production without irrigation.However,the lack of environmentally friendly and durable covering material is a key factor limiting the sustainable development of ridge-furrow rainwater harvesting technology.This study explored the effect of ridge-furrow rainwater harvesting with biochar application on soil erosion and alfalfa productivity,thereby improving the adaptability of this technology to environmental variability,and providing solutions for obstacles faced by ridge-furrow rainwater harvesting planting in a new way.In this study,a field experiment was conducted to study the effects of ridge-furrow rainwater harvesting with biochar application on soil properties,soil erosion,alfalfa fodder yield,forage quality,water use efficiency,and production economics in a split-plot experimental design.The main plot consisted of two biochar application modes(biochar(30t ha-1)and no-biochar(0 t ha-1))using no-biochar as a control,while the sub-plots consisted of three tillage modes（tied-ridging,open-ridging,and flat planting）using flat planting as a control.The main results are as follows:Compared to flat planting,under biochar application,the runoff,runoff coefficient,and sediment deposition for tied-ridging reduced by 27.95%,35.13%,and 76.01%,respectively,while the corresponding values for open-ridging reduced by 18.86%,19.31%,and 57.68%;Under no-biochar application,the runoff,runoff coefficient,and sediment deposition for tied-ridging reduced by 51.96%,53.72%,and 81.57%,respectively,while the corresponding values for open-ridging reduced by 30.45%,35.71%,and 69.78%.Biochar application significantly（P<0.05）resulted in lower total runoff,runoff coefficient,and sediment deposition than no-biochar application.The runoff,runoff coefficient,and sediment deposition under biochar application were 39.33,40.78,and 54.12 times great than that under no-biochar application,respectively.Compared to flat-planting,under no-biochar application,the total phosphorus and p H in topsoil（0-10 cm）for tied-ridging increased by 7.37%and 0.06%,respectively,while,the total nitrogen and available phosphorus decreased by 20.52%and 9.86%.The total phosphorus in topsoil for open-ridging increased by 7.37%,while the total nitrogen,available phosphorus,and p H for open-ridging decreased by 17.47%,43.17%,and 0.06%,respectively.Under biochar application,the available phosphorus and p H in topsoil for tied-ridging increased by 81.85%and 0.81%,respectively,while the total soil phosphorus and total nitrogen for tied-ridging decreased by 3.77%and 25.42%.The total phosphorus and available phosphorus in topsoil for open-ridging increased by 21.70%and 42.93%,respectively,while total nitrogen and p H for open-ridging decreased by 15.68%and 1.25%.The total phosphorus and available phosphorus under biochar application were 0.00 and24.23 times great than that under no-biochar application,respectively,while the total nitrogen and p H under no-biochar application were 5.61 and 0.75 times great than that under biochar application,respectively.Compared to flat planting,under biochar application,the soil temperature on ridges in0-25 cm soil layers for tied-ridging and open-ridging decreased by 2.36℃and 1.25℃,respectively,under no-biochar application;while the corresponding values for tied-ridging and open-ridging decreased by 5.34℃and 2.63℃,under biochar application.The soil temperature on ridges under biochar application was 0.82 times great than that under no-biochar application.The soil desiccation index for tied-ridging and open-ridging decreased by 3.33%and 9.34%,respectively,under no-biochar application,while the corresponding values for tied-ridging and open-ridging decreased by 6.45%and 10.52%,under biochar application.The soil desiccation index under biochar application was 7.25 times great than that under no-biochar application.Compared to flat planting,alfalfa fodder yield for tied-ridging and open-ridging increased by 19.32%and 19.69%,respectively,under no-biochar application;while the corresponding values for tied-ridging and open-ridging increased by 27.57%and 22.98%,under biochar application.Alfalfa fodder yield under biochar application was 1.37 times great than that under no-biochar application.Water use efficiency for tied-ridging and open-ridging increased by 12.00 and 9.00 kg ha-2 mm-1,respectively,under no-biochar application;while the corresponding values for tied-ridging and open-ridging increased by16.00 and 13.00 kg ha-2 mm-1,under biochar application.The water use efficiency under biochar application was 1.18 times great than that under no-biochar application.Compared to flat planting,under no-biochar application,crude protein,acid detergent fiber,digestible nutrients,digestible dry matter,and lactation net energy of alfalfa for tied-ridging increased by 11.86%,3.70%,8.34%,4.38%,and 6.31%,respectively,and neutral detergent fiber for tied-ridging decreased by 11.13%.Alfalfa crude protein,acid detergent fiber,digestible dry matter,and lactation net energy of alfalfa for open-ridging increased by18.92%,2.18%,4.16%,and 6.04%,respectively,and neutral detergent fiber and digestible nutrients for open-ridging decreased by 10.87%and 10.87%.Under biochar application,crude protein,acid detergent fiber,digestible dry matter,and lactation net energy of alfalfa for tied-ridging increased by 57.24%,1.86%,3.29%,and 4.99%,respectively,while neutral detergent fiber and digestible nutrients for tied-ridging decreased by 17.65%and 17.65%.Crude protein,neutral detergent fiber,and digestible nutrients for open-ridging increased by56.47%,9.41%,and 9.41%,respectively,while acid detergent fiber,digestible dry matter and lactation net energy for open-ridging decreased by 1.40%,1.58%,and 2.36%,respectively.Crude protein,acid detergent fiber,digestible nutrients,neutral detergent fiber,digestible dry matter,and net energy for lactation of alfalfa under biochar application were1.10,1.11,1.02,1.03,1.00,and 1.00 times great than that under no-biochar application,respectively.Compared to flat planting,the feeding value of alfalfa for tied-ridging and open-ridging increased by 4.53%and 0.72%,respectively,under no-biochar application;while the corresponding values for tied-ridging and open-ridging increased by 16.22%and 20.32%,under biochar application.The feeding value of alfalfa under biochar application was 1.75times great than that under no-biochar application.Compared to flat planting,the net benefits in tied-ridging and open-ridging increased by 17.89 and 17.63 RMB ha-1,respectively,under no-biochar application;while the corresponding values for tied-ridging and open-ridging increased by 26.56 and 21.56 RMB ha-1,under biochar application.The net benefit under biochar application was 42.57 times great than that under no-biochar application.This study confirmed that tied-ridge-furrow rainwater harvesting system with biochar application has potential to improve alfalfa productivity,food security,and production economics,and is an effective measure to promote the sustainable production of alfalfa in the semi-arid Loess Plateau. |
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