Nitrogen in soil, plant and atmosphere after limestone and gypsum application on no-tillage system

Abstract

The dynamics of nitrogen (N) in the soil-plant-atmosphere system can be influenced by the superficial application of limestone and gypsum. The objective of this research was to evaluate the changes in N balance and cycling in a no-tillage system as a function of soil acidity correction using limestone and by the application of gypsum and N rates. An experiment was carried out under field conditions, in Botucatu-SP, with soybean cultivation as the summer crop followed by the maize and brachiaria consortium in the off-season, in the agricultural years from 2016 to 2018. The experimental design in a randomized block design, with four replications, with a total of 48 experimental units, consisting of treatments in a factorial scheme (3x4), being: control, limestone application and limestone + gypsum and 4 rates of N (N = 0, 80, 160, 240 kg ha-1 of N), applied in the maize crop. The soil of the area will be sampled (0-10, 10-20, 20-40, 40-60 and 60-80 cm depth) prior to the application of the treatments and before soybean sowing in the years 2016, 2017 and 2018, N-total, N-inorganic, N-organic, N-microbial, N losses due to leaching and soil fertility were evaluated. The moisture of the soil profile will be monitored by means of a capacitive probe (Diviner 2000®) that will correlate the losses of N-NO3- and N-NH4 + by leaching to the soil solution, which will be collected by extractors with porous capsule. N losses to the atmosphere via NH3 and N2O will also be monitored. Monthly the straw will be collected on the soil and will be evaluated by determining the mass of the dry plant residues and also the N contents. In both cultures will be evaluated: nutritional status, root quantification, grain yield and N in the beans. At the end of the experiment the balance of N in the system will be determined. The results will be submitted to analysis of variance, Tukey test, correlation and polynomial regression. (AU)