Adubação de sistemas: antecipação de nitrogênio e potássio em solos arenosos e argilosos

Abstract

The use of sustainable activities has been increasing in recent years. Factors related to population growth expectations, increased food production and the irrational use of fertilizers have been pressuring the agricultural sector in search of more efficient management. Among the main practices that can be used, the Integrated Crop-Livestock- System, the No-till, and the use of Fertilization-Level Systems, using nutrient cycling, stand out. Although these practices can be used on farms, there is still a need for further studies related to the type of soil, its management, nutrient dynamics, and the effect on plants. Based on this, the objective of the work was to understand the effect of fertilization systems for nitrogen and potassium in clayey and sandy soils. The present work was composed of three different experimental protocols. The first experiment was conducted in the municipality of Catanduvas/PR in the 2018/2019 harvest. The experimental design used was a randomized block design with four repetitions and subdivided plots in time and space. The treatments consisted of two strategies for anticipating nitrogen fertilization, with the application of 45 kg N ha−1 at pasture tillage and the application of 45 kg N ha−1 at pasture tillage + 140 kg N ha−1 on the pasture straw after desiccation. The second study factor was applied to the subplots and consisted of nitrogen application at doses of 0, 100, 200, and 300 kg N ha−1 on corn cover crop. In addition, corn plants were collected at 55, 87, and 118 days after sowing. The second experiment was conducted in the municipality of Pato Branco/PR in the years 2016 and 2017. The experiments were conducted in a randomized block design with four repetitions. In the first year, the millet crop was evaluated. The first factor studied was the use of ground cover or fallow on the area. The second factor was composed of application periods of 200 kg N ha−1 of millet (15, 30, and 45 days after sowing). Also, plant collections were performed at 20, 27, 34, 41, 48, 55, 62, and 69 days after sowing. For the second year, the corn crop was evaluated. The first factor evaluated was N doses applied to the pasture straw (0 and 150 kg N ha−1). The second factor was composed of N doses applied on the corn crop cover grown in sequence (0 and 150 ha−1). Plant collections were also performed at 37, 44, 51, 58, 69, 90, and 149 days after sowing the corn crop. The third experiment was conducted in the municipality of Para´ıso das A´ guas/MS during the 2019/2020 crop. The experimental design was a randomized block design with four repetitions. The first factor studied was potassium doses applied on the pasture straw (0 and 120 kg K2O ha−1). The second factor was potassium doses (0, 30, 60, and 120 kg K2O ha−1) applied to the soybean crop cover crop. Collections of litter-bags were made at 0, 15, 30, 60 and 90 days after deposition. The early application of nitrogen on the pasture and its stubble results in better nutritional conditions and grain productivity of the corn crop, being an alternative to be used in the properties. Furthermore, the dilution curves tool was shown to be a good indicator of the nutritional status of corn plants. For the anticipation of fertilization, the application performed 15 days after sowing was the one that presented the best results for the millet crop. The cultivation of millet in places that presented ground cover resulted in plants better nourished for nitrogen. Moreover, the anticipation of nitrogen fertilization on black oat straw does not harm the grain yield and nutrition of corn plants. The anticipation of potassium fertilization on sandy soil can be carried out without affecting the grain yield of soybeans. Potassium application on brachiaria alters its decomposition kinetics and nutrient release. There was no evidence of potassium losses through leaching into the soil.