Integration of ridge and furrow rainwater harvesting systems and soil amendments improve crop yield under semi-arid conditions

Low crop productivity due to prolonged droughts, inappropriate water saving practices, low soil fertility and soil erosion is a major threat to food security in semi-arid areas. In these areas, ridge and furrow rainwater harvesting (RFRH) technique is widely adopted to minimize water deficiency problems. Incorporating mulching in ridge and furrow rainwater harvesting (RFRH + M) is also being promoted to increase water storage and conservation for crop usage. Till date, evidence establishing the efficacy of incorporating mulching and biochar in ridge and furrow system, and modalities for improving crop yield has not been synthesized quantitatively to promote widespread adoption. The objective of this MA was to assess the whether the integration of ridge and furrow rainwater harvesting systems (RFRHs) with soil amendments, namely biochar or mulches affect crop yield and soil properties relative to traditional no-till flat planting. In addition, the MA investigated how factors such as such as precipitation moderate the performance of RFRHs with soil amendments in different regions in China was investigated. A meta-analysis (MA) of data from 42 published articles based on PRISMA guidelines was used to assess the impacts of ridge and furrow tillage with and without mulching on potato (Solanum tuberosum, L.), wheat (Triticum aestivum, L.), and maize (Zea mays, L.) yield relative to traditional no-till flat planting in the Loess Plateau of China. Mulch materials were plastic and straw in addition to biochar amendment. RFRH + M significantly affected crop yield in Gansu, Ningxia, Shanxi and Shaanxi regions of the Loess Plateau. Plastic film mulched ridge-furrow planting compared with flat planting without mulching increased potato yield by 34.01% in Gansu, 32.99% in Ningxia, and 12.78% in Shanxi. Maize yield increased by 33.10% in bare ridge-furrow planting with mean of 10,936.81 kg ha−1 compared with flat planting with a mean of 8217.07 kg ha−1. Conversely, in areas where precipitation was higher than 500 mm, integrated plastic film with straw in ridge-furrow significantly (p < 0.00001) increased wheat yield by 60% compared to flat planting without mulching, which can be attributed to the soil alkalinity (pH > 7–8) of the soils in these areas. The observed differences in crop yield could also be ascribed to the influence of phosphorus availability. Results from the MA showed that the effect of straw mulched-ridge-furrow on crop yield was stronger in soils with higher available phosphorus at 20 mg kg−1 (5.31%; p = 0.0003) than flat planting without mulching. Findings of the MA suggest that the adoption of integrated plastic film mulch with straw in ridge and furrow system can improve soil properties and crop yield under rain-fed conditions. Compared with flat planting without mulching, incorporating plastic film mulch and straw in ridge and furrow systems averts residual plastic film accumulation on farmlands, which could impede plant growth, soil structure, water and nutrient uptake in rain-fed agriculture in semi-arid areas.