Can additional agricultural resource inputs improve maize yield, resource use efficiencies and emergy based system efficiency under ridge-furrow with plastic film mulching?

Abstract

Water scarcity is a major constraint for maize production in drylands. As an efficient water-saving technology, the ridge-furrow with plastic film mulching (RM) system has achieved success in dryland farming. The efficiency of the rainwater-harvesting system in RM is greatly affected by erratic precipitation, and water absorption by crops is influenced by nutritional availability. Whether the additional supply of irrigation and nitrogen (N) resources under the RM system could influence the resource use efficiencies, emergy flows, and system efficiency of agricultural products is unclear. Therefore, a 3-year field study on maize plants consisting of four planting patterns (CP: conventional planting; RM; RM + SI: RM plus supplementary irrigation; RM + SI + N: RM + SI plus additional N fertilizer) was conducted from 2018 to 2020 in the Loess Plateau of China to determine resource use efficiencies, emergy flows, and system efficiency through emergy evaluation. In this study, we demonstrated the high efficiency of the micro-field rainwater-harvesting system of RM by collecting more rainwater and improving soil hydrothermal conditions. For example, the soil temperature and moisture of topsoil at seedling stage were increased by 4.3 °C and 13%, respectively, under RM compared with CP. The soil hydrothermal conditions in RM further improved maize yield (+35%), water use efficiency (+32%), N partial factor productivity (+37%), radiation use efficiency (+10%), and system efficiency (8%, from an emergy perspective), compared to CP. However, the additional supply of N or irrigation in RM + SI or RM + SI + N planting patterns failed to increase resource use efficiency, although the maize yield was increased by 9%. Furthermore, although the total emergy input was increased by 19%, it did not significantly increase energy output, and thus decreased the resource efficiency by 9% through emergy evaluation, compared to RM. Overall, RM without additional agricultural resource input could be recommended as a sustainable and cleaner production strategy for maize in drylands to address the issues of ever-increasing food demand and declining availability of production resources.