Nitrogen transfer in the intercropping system between organic cherry tomato and legumes in succession to green corn

Author(s)

Gabriela Cristina Salgado

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB)
• Defense date: 2022-02-18

Examining board members

Paulo Cesar Ocheuze Trivelin; Anastácia Fontanetti; Simone da Costa Mello; Fernando Angelo Piotto

• Advisor: Paulo Cesar Ocheuze Trivelin; Edmilson José Ambrosano

Abstract

The main study aim was to investigate the N transfer from different legumes to cherry tomato in the intercropping system under residual straw of the previous green corn crop using the 15N natural abundance method. There also were evaluated yield and nutrients concentration of the plants, soil fertilizer, cost and profitability of this organic system. The experiment was in a randomized complete block design with five replications and eight treatments: monocrop of cherry tomato adding the residual green corn crop residue (straw) as a mulch, a monocrop of cherry tomato without straw, cherry tomatoes intercropped with jack bean, sun hemp, dwarf velvet bean, mung bean, white lupine or cowpea bean grown as green manures, in two consecutive cycles. In 2011, the number and weight of the total and the marketable fruits of tomatoes were 70% - 88% higher than in 2012, and the number of damaged fruits was 12 % lower in 2011 than in 2012. The different treatments had no effect on the yield of the green corn in 2012 and 2013. There was no difference in BNF between legumes at 100 days after sowing, independent of the year. The BNF was responsible for more than half of the N accumulated in the legumes. The N of legumes was transferred to cherry tomato in similar quantities, and the leaves and fruits of cherry tomato received more N transfer than shoots. It was shown that N transfer increases with the growth/development of cherry tomato. The legume in an intercropping system with cherry tomato cultivated in the succession of green corn does not provide sufficient nitrogen to supply the green corn demand. In relation to green corn straw, the single exponential decay function fitted with the decrease of the decomposition time in the dry matter remaining of green corn straw in 2011 and 2012. In the same way, the exponential decay function fitted with the decrease of the decomposition time of the C and N release from the mass decomposition of green corn straw. However, the residual green corn straw under cherry tomato with different legumes in an intercropping system did not increase the straw decomposition rate and the C and N release from straw decomposition. The 13C decreased and the 15N tended to increase in the green corn straw during the decomposition time. The total C and N content and the C and N stock of the soil increased over the years, especially in 2013. The soil C:N ratio also increased over the year, the C accumulated was higher than the N accumulated, increasing the N immobilization in the system. The soil organic matter reduced over the years, although the total C and N increased, suggesting that the organic C and N decreased, and the inorganic C and N increased in the soil. This agricultural system reduced the soil fertility, although the N and C total stock in the soil increased over the year. Furthermore, it showed high profitability under the conditions in which this study was conducted. (AU)

• FAPESP's process: 18/25483-8 - Nitrogen transfer in the intercropping system with organic cherry tomato and legumes in succession to corn-green
• Grantee: Gabriela Cristina Salgado
• Support Opportunities: Scholarships in Brazil - Doctorate