Residual and immediate effect after 16 applications of organic sources on yield and nitrogen use efficiency in black oat and corn

ABSTRACT Soils with a long-term history of animal manure application exhibit higher residual effects of nitrogen (N) in soil and can affect the efficiency with which N will be used. This study aimed to evaluate how the immediate and residual effect of 16 applications of animal manure reflects on yields of black oat and corn rotation system, as well as N use efficiency. The study was carried out in no-tillage from 2004 to 2016 in Brazil. The treatments were pig slurry (PS), dairy slurry (DS), pig deep-litter (PL), mineral fertilizer (MF), and control (C). Prior to the sowing of black oat, in which 16 animal manure applications had already been made, an area of the soil was delimited where the treatments were not applied. This area was referred to as unfertilized (U) soil. Applications were carried out in the remaining area and were referred to as fertilized (F) soil. The highest dry matter yield and N accumulation in black oat and corn were found in F soils treated with DS and PL, respectively. In corn, the highest grain yield and N accumulation in grains were found with DS and PS. In U soil, the 16 applications (of DS especially) resulted in yields and N accumulation greater than the control and MF, but lower than those in F. The highest N use efficiency was found with DS. The history of animal manure applications was not enough to rule out additional applications in the following years.

摘要
长期施用畜禽粪便的土壤会保留更高的氮（N）残留效应，并可影响氮素的利用效率。本研究旨在评估16次畜禽粪便施用的即时效应与残留效应对黑燕麦-玉米轮作系统产量及氮素利用效率的影响。本试验于2004年至2016年在巴西采用免耕法（no-tillage）开展。试验设置5种处理：猪粪浆（pig slurry, PS）、奶牛粪浆（dairy slurry, DS）、猪深层垫料（pig deep-litter, PL）、矿物肥料（mineral fertilizer, MF）以及对照组（control, C）。在已完成16次畜禽粪便施用的黑燕麦播种前，划定一块未施加任何试验处理的土壤区域，记为未施肥（U）土壤；剩余区域则进行肥料施用，记为施肥（F）土壤。
黑燕麦与玉米的最高干物质产量及氮素累积量分别出现在施用猪深层垫料（PL）与奶牛粪浆（DS）的施肥土壤中。玉米籽粒产量与籽粒氮素累积量最高的处理分别为奶牛粪浆（DS）与猪粪浆（PS）。在未施肥（U）土壤中，经16次畜禽粪便施用（尤其是奶牛粪浆（DS））后的产量与氮素累积量均高于对照组（C）与矿物肥料（MF）处理，但低于施肥（F）土壤。氮素利用效率最高的处理为奶牛粪浆（DS）。畜禽粪便的长期施用历史并不足以排除后续年份追加施用的必要性。