Reduced fertilization boosts soil quality and economic benefits in semiarid apple orchard: A two-year appraisal of fertigation strategy

Long-term overfertilization not only aggravates environmental costs, but reduces the quality and yield of fruit in dryland apple orchard, and this issue is closely associated with post-germination fertilization management. On the basis of multi-year observations, we developed a targeted fertigation strategy of FORD, i.e. formula fertilization (rational fertilizer scheme), on-demand fertilization in the sensitive period, reduced fertilization and delayed fertilization. Two-year field investigations were conducted with conventional furrow application (CK), integrated furrow and injection application (FI) and the optimized injection application under the FORD principle in a semiarid apple orchard. The data indicated that FI and FORD had a similar fruit yield of 57.2 Mg ha-1, significantly greater (by 4.5%) than CK. Yet, fruit quality (nutrition, flavor and appearance) was substantially improved under FORD, relative to FI and CK (P<0.05). Importantly, FORD did not induce secondary salinization (soil electric conductivity (EC) of 100-500 μs cm-1, pH of 7.8), but significantly improved soil microbial biomass carbon and the activities of carbon turnover key enzymes (β-glucosidase and cellobiohydrolase). As a result, FORD induced a better functioning of leaves, and a faster speed of fruit expansion than CK and FI did. Totally, the above parameters were positively associated with the efficient couplings of water and fertilizer, which critically depended on nutrients rational supply in FORD. Notably, relative to CK and FI, FORD reduced the fertilization cost by 27.8% and 8.3% respectively, accordingly harvesting 38.1% and 11.6% higher net economic return (2.94×104 US$ ha-1). In summary, there existed remarkable positive effects of FORD-led fertigation strategy on fruit yield, quality and economic benefits. The FORD can be viewed as a general environment-friendly strategy to guide apple post-germination fertilization management for greater economic benefits.