Objectives Water-conserved cultivation and fertilizer management have been the research focus in dryland cropping systems of China. Most attention has concentrated on yield formation and water utilization, less research on crop nutrient uptake and utilization. We investigated the effects of ridge mulching, furrow seeding, and optimized fertilizer placement on uptake and utilization of nitrogen (N), phosphorus (P) and potassium (K) and in order to provide a theoretical basis for high-yield and profitable production of wheat in drylands.
Methods A continuous experiment in the fixed plots was conducted in the typical dryland of central Loess Plateau in the climatically normal year of 2013–2014, wet year of 2014–2015 and dry year of 2015–2016. Winter wheat was sown in three patterns: conventional flat pattern without plastic film mulching but with uniform fertilization (CP), ridge mulching, furrow seeding with uniform fertilization (RF), and ridge mulching, furrow seeding with side-dressed fertilization under plastic film (RFF). Yield, economic return, and nutrient uptakes and distributions, nutrient harvest indexes, nutrient uptake efficiencies, fertilizer partial factor productivities for N, P and K, and physiological efficiencies and requirements of N, P and K for grain yields were analyzed.
Results Compared with CP, the yield under RF was increased by 9.5% and 6.3%, respectively, but the economic return and the rate of output to input under RF had no significant changes. In the normal year and dry year, RFF significantly increased the economic return and ratio of output to input by 23.4% and 9.1% compared with CP, and 21.5% and 14.6% compared to RF, averaged across the three years. Compared with CP, RF had no significant effects on NPK uptake efficiencies due to the decreased NPK uptakes after jointing stage of winter wheat, but it increased the N physiological efficiency and NPK fertilizer partial factor productivities by 7.7%, 7.1%, 8.1% and 6.7%, respectively, and decreased the N requirement for 100 kg grain by 8.7%. Although RFF did not affect the NPK harvest indexes, NPK physiological efficiencies and NPK requirements for 100 kg grain, it increased the average NPK uptake efficiencies by 18.4%, 22.1% and 16.4% and NPK fertilizer partial factor productivities by 16.0%, 16.8% and 15.6%, respectively compared with CP. Compared with RF, RFF increased the NPK uptakes at anthesis and maturity and NPK distributions in straw and grain at maturity, and thus significantly increased NPK uptake efficiencies by 20.8%, 18.0% and 12.1%, NPK fertilizer partial factor productivities by 8.3%, 8.1% and 8.4%, NP requirements for 100 kg grain by 28.3% and 10.0%, but decreased NP harvest indexes by 3.9% and 4.2%, NP physiological efficiencies by 9.5% and 8.1%, respectively, averaged across the three years.
Conclusions Ridge mulching, furrow seeding with uniform fertilization could decrease the N requirement and increase the N physiological efficiency and NPK fertilizer partial factor productivities, but not increase the overall economic return. Ridge mulching, furrow seeding with side-dressed fertilization under plastic film is beneficial for NPK uptakes at different growth stages, and thus increases economical return, nutrient uptake efficiencies and fertilizer partial factor productivities for N, P and K, but special attention should be paid to the decreased NP physiological efficiencies and the increased NP requirements under this practice.
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