Plantas de cobertura de verão em cultivo solteiro no fornecimento de nitrogênio para o milho safrinha

Abstract

In the southern region of Brazil, the most utilized agricultural model is the no-tillage system of planting, with the usage of cover crops, mostly in winter, which is scarcely used during summer. The usage of cover crops is normally delineated as mere tool to diminish the growth and establishment of spontaneous plants, not being taken in account the recycle or nutrients fixation potential of these crops. The following study aimed to evaluate the usage of cover plants on summer single crops, for nitrogen supply on serafin maize. The search was conducted during the agricultural years 2017/2018 in Cerro Largo-RS, at Latossolo Vermelho. In a randomized block design, with plots (10 X 3,5 m) with 4 replicates, were established with cover crops and posterior subdivided in a subgroup culture, the maize, with or without nitrogen fertilization. Five cover crops were evaluated, millet (Pennisetum glaucum L), sudan grass (Sorghum bicolor cv. sudanense), crotalaria juncea (Crotalaria juncea L), jack beans (Canavalia ensiformes) and land set-aside of single crops. The evaluation of dry matter yield assessments of the area (DMYA), cumulated nitrogen quantity (N), decomposing and liberation of N from DMYA of cover crops were developed. During the cultivation of maize were evaluated the mineral N content in the soil, the grain yield and weight of a thousand grains (WTG). The millet produced the greater quantity of DMYA and accumulated an N quantity similar to the jack beans, despite this legume had produced 52% of DMYA of the gramineae. The jack beans, millet and crotalaria crops increased the maize productivity in comparison to the land set-aside and to the sudan grass when not utilized the mineral N. Even with N supplement for the maize, the cover crops increased the grain productivity, particularly with the usage of jack beans and millet.