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Purpose: Environmentally friendly mulching material and appropriate tillage practice are needed to solve plastic film residues in agricultural production in ridge-furrow rainwater harvesting technology (RFRHT) in the Loess Plateau in China. Materials and methods: A field experiment in randomized block design was conducted to (1) investigate the runoff coefficient for three ridge widths (30, 45, and 60 cm) using three ridge mulching materials (ridges compacted with soil (RCS), maize straw biochar-soil mixture (SBM), and cow dung biochar-soil mixture (DBM)); (2) the effects of three ridge widths using three ridge mulching materials on soil moisture, temperature, nutrients, fodder yield, quality, and water use efficiency (WUE) of sainfoin and conventional flat planting (FP) as a control, during two consecutive sainfoin-growing years: 2017 and 2018. Results: The predicted runoff coefficient for RCS30, RCS45, RCS60, SBM30, SBM45, SBM60, DBM30, DBM45, and DBM60 (subscripts 30, 45, and 60 referred to ridge widths) was 0.31, 0.33, 0.34, 0.26, 0.30, 0.31, 0.22, 0.24, and 0.25, respectively, over 2 years. DBM had a higher concentration of total nitrogen and organic matter compared to SBM, while SBM had a higher concentration of Olsen phosphorus and available potassium compared to DBM. The higher runoff coefficient and soil moisture in SBM led to higher fodder yield, WUE, and condensed tannin content of sainfoin, compared to DBM. Compared to FP, in RCS, fodder yield and WUE of sainfoin decreased by 8.8–17.8% and 0.6–2.6 kg ha−1 mm−1, respectively. Condensed tannins concentration of sainfoin for RCS, SBM, and DBM increased by 4.1 −9.0%, 11.4 −21.8%, and 9.4 −15.2%, respectively. Fodder yield in SBM and DBM increased by 14.3 −19.5% and 7.1 −10.0%, respectively, while WUE in SBM and DBM increased by 6.7 −8.5 and 4.7 −5.5 kg ha−1 mm−1. Conclusion: Ridges compacted with biochar-soil mixture, especially with maize straw biochar-soil mixture, increased fodder yield, WUE, and condensed tannin content of sainfoin. The optimum ridge width in SBM and DBM for sainfoin production was 46–49 and 41 cm, respectively. [ABSTRACT FROM AUTHOR]

Background. Loss of organic matter and mineral nutrients to soil erosion in rain- fed agriculture is a serious problem globally, especially in China’s Loess Plateau. As a result, increasing rainwater usage efficiency by tied-ridge-furrow rainwater harvesting with biochar is expected to improve agricultural productivity. Nonetheless, with limited knowledge on tied-ridge-furrow rainwater harvesting with biochar, small-scale farmers face the challenge of adoption, thus, the rationale for this study. Materials and methods. A field experiment was conducted to determine the influence of open-ridging (OR) and tied-ridging (TR) with bio-degradable film on ridges and biochar in furrows on runoff, sediment losses, soil moisture, fodder yield, and water use efficiency (WUE) on sloped land, using flat planting (FP) without ridges and furrows as control, during alfalfa-growing year (2020). Results. Runoff in flat planting (30%), open ridging (45%), and tied ridging (52%) were decreased with biochar to the extent where sediment was decreased in flat planting (33%), open ridging (43%), and tied ridging (44%) as well. The mean runoff efficiency was lower in flat planting (31%), open ridging (45%), and tied ridging (50%) in biochar plots compared to no-biochar plots. In biochar and no-biochar plots, soil temperature on ridges of TR was higher than that on OR, which was higher than FP during alfalfa growing season. Soil temperature in furrows during alfalfa growing season in biochar and no-biochar plots were in the order FP > OR > TR. Mean soil water storage for FP, OR, and TR, in biochar plots was higher than in no-biochar plots. This indicates biochar has a beneficial impact on open riding. Total annual net fodder yield (NFY) was significantly (p = 0.00) higher in treatments in the order TR > OR > FP. Tied ridging had a significant effect on actual fodder yield (AFY) in biochar plots, while open ridging significantly affected AFY in no-biochar plots. Annual total mean NFY and AFY increased by 8% and 11% in biochar plots compared to no-biochar plots. In biochar and no-biochar plots, water use efficiency was in the order TR > OR > FP. Conclusively, water use efficiency was significantly higher (p = 0.01) in biochar plots compared to no-biochar plots. Conclusion. When crop production is threatened by soil erosion and drought, mulched tied-ridge with biochar is beneficial to crop growth in rain-fed agriculture, according to this research. Smallholder farmers should be trained on applying this technique for water-saving to mitigate runoff, soil erosion, sediment losses, and improve food security in semiarid areas. [ABSTRACT FROM AUTHOR]

Ridge-furrow rainwater-harvesting (RFRH) has emerged as an effective technology to mitigate drought stress, control soil erosion, and increase crop yield in semiarid regions of China. However, the use of plastic film mulch in RFRH makes this technology impractical. A field experiment was conducted for three consecutive years in a randomized complete block design to determine 1) the runoff coefficient for ridges compacted with soil mixed with two types of biochar (rice straw biochar and cow dung biochar) at two application rates (single application rate i.e., 3 × 104 kg ha−1; and double application rate i.e., 6 × 104 kg ha−1; and 2) the effects of the ridges compacted with soil mixed with two types of biochar at two application rates on soil physico-chemical properties, economic benefit, fodder yield and water use efficiency (WUE) of alfalfa, and ridges compacted with soil (no biochar) as control. The average runoff coefficient for NB, SRSB, DRSB, SCDB, and DCDB (NB, SRSB, DRSB, SCDB, and DCDB were ridges compacted with soil, compacted with soil mixed with single rice straw biochar application, double rice straw biochar application, single cow dung biochar application, and double cow dung biochar application, respectively) over these three years was 31%, 28%, 27%, 22%, and 21%, respectively. Ridges compacted with soil-biochar crust had lower runoff coefficients, soil water storage, net income, and higher soil nutrients, when compared to ridges compacted with soil. The topsoil temperature at ridge tops was affected by the ridges compacted with soil-biochar crust, but the topsoil temperature at furrow bottoms was not affected. Compared to ridges compacted with soil mixed with cow dung biochar, ridges compacted with soil mixed with rice straw biochar had lower soil nutrients, and higher soil water storage resulting in higher fodder yield and WUE of alfalfa. With runoff, the nutrients in biochar flowed from ridges to furrows, becoming usable for plants. Ridges compacted with soil-biochar crust increased topsoil nutrients, especially soil organic matter ranging from 15% to 34%, resulting in high fodder yield and WUE of alfalfa. Compared to NB, annual fodder yield for SRSB, DRSB, SCDB, and DCDB increased by 9.0%, 5.9%, 4.4%, and 3.8%, respectively, over three years, while WUE for the same treatments increased by 2.81, 1.95, 0.65, and 0.45 kg ha−1 mm−1. Rice straw biochar at an application rate of 3 × 104 kg ha−1 was found to be suitable type of biochar for increase in fodder yield and WUE of alfalfa in RFRH. Future studies should be conducted in the form of long-term field study to determine economic benefits of biochar application. • Ridges compacted with soil-biochar had low runoff coefficient, soil moisture, and high soil nutrients. • High topsoil nutrients, especially organic matter, resulted in high fodder yield and WUE of alfalfa. • As biochar application rate increased, runoff coefficient and soil moisture decreased, while soil nutrients increased. • Rice straw biochar resulted in low soil nutrients and high soil moisture, compared to cow dung biochar. • Rice straw biochar (3 × 104 kg ha−1) was suitable form in ridge-furrow rainwater-harvesting. [ABSTRACT FROM AUTHOR]