Soil carbon fractions and mineralizable nitrogen in a crop-livestock system

• Grant number: 20/16651-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2021
• End date: September 30, 2021
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Mara Cristina Pessôa da Cruz
• Grantee: Henrique Fontellas Laurito
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

In research on soil management, organic matter is often fractionated, with emphasis on the labile fraction, which is the most sensitive to changes in management and the most directly associated with nutrient cycling. This sensitivity allows us to save time to recommend the best strategies or propose adjustments in management to increase soil quality and sustainability of production systems. The objectives of this project are to evaluate particulate organic carbon (pOC) and mineralizable organic N in a crop-livestock integration system (CLI) in which different corn and marandu grass sowing systems were tested in the integration. The experiment was installed in 2015 at the Cattle Research Center of Sertãozinho, belonging to the Institute of Animal Science/APTA/SAA. The design of the experiment was randomized blocks with six treatments and three replications. The treatments were: Tillage (corn for grains); Livestock (marandu grass); CLI1: corn plus marandu grass with simultaneous sowing in planting fertilization; CLI2: corn plus marandu grass with simultaneous sowing in planting fertilization + application of nicosulfuron herbicide; CLI3: corn plus marandu grass with marandu grass sowing in corn cover fertilization; CLI4: corn plus marandu grass with simultaneous sowing of marandu grass in the corn line and between line + application of the herbicide nicosulfuron. The experiment was conducted until January 2018, when soil samples were collected at depths of 0-10 cm and 10-20 cm, which will be incubated at 25oC for 28 days. The pOC will be determined in the samples before and after incubation. Mineralized N will be evaluated at the end of the incubation. The effects of treatments on pOC levels before incubation and mineralized N will be evaluated using variance analysis by the F test, considering a randomized block design in subdivided plots. Corn and grass monocultures and sowing systems within the CLI will be considered main treatments, and depths, secondary treatments. In case of significance, means will be compared by the Tukey test. The difference between the pOC before and after incubation will be calculated and this difference will be subjected to variance analysis and comparison of means, and will also be correlated with mineralized N data.