INTERACTIONS BETWEEN GREEN MANURE AND ROCK PHOSPHATE ON SOIL NUTRIENT CYCLING ON FAMILY FARMS

Marcelo Henrique Siqueira Leite,Eduardo Guimarães Couto,Jennifer Marie Blesh

doi:10.1590/1983-21252022v35n102rc

Marcelo Henrique Siqueira Leite, Eduardo Guimarães Couto + Show 1 more

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https://doi.org/10.1590/1983-21252022v35n102rc

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Abstract

ABSTRACT Family farming is important for the production of food for human consumption, but it lacks resources to invest in the soil fertility of its crops. The objective of this study was to analyze whether the use of green manures increases soil fertility in terms of the nutrients N, P and K with low environmental risk for family agricultural production. An experiment was set up in the State of Mato Grosso (Brazil), in randomized complete block design, with a 6 x 3 factorial scheme, four replications, corresponding to 6 types of plants and 3 doses of phosphorus. Leguminous green manure plants were: velvet bean, Crotalaria juncea, Crotalaria ochroleuca and dwarf pigeon pea, in addition to plots with pearl millet and weedy fallow control. Rock phosphate (i.e., reactive natural phosphate) was applied as a source of phosphorus at 0, 50 and 100 kg P2O5 ha-1. The species used as green manure were cut in full bloom and the levels of N, P, K and C in plants and soil were determined. Leguminous green manure plants, after mineralization, increased the stocks of N, P and K in the soil. Crotalaria juncea was the one that reached the highest N accumulation in its constitution, being recommended in the intercropping with species with C/N ratio > 30 to minimize risks of contamination with nitrate in the soil. This work concluded that the managements with green manure plants, especially Crotalaria ochroleuca, are recommended and environmentally safe technical alternatives for family farming.

Highlights

In recent decades, the intensification of agriculture has achieved its goal of increasing yield in the field, but with the use of large amounts of fertilizers (SILVA et al, 2014)
The highest values of N in the dry mass (DM) of the green manure plants were found in the species Crotalaria juncea (CJ), Crotalaria ochroleuca (CO) and pigeon pea (PP)
The results of this study indicate that the green manure plants at the end of the experiment added C and N to the soil in a balanced way, which will be used by microorganisms, improving soil quality and increasing the contents of nutrients for food production in family farming

Summary

Introduction

The intensification of agriculture has achieved its goal of increasing yield in the field, but with the use of large amounts of fertilizers (SILVA et al, 2014). Despite being a major fertilizer consumer, Brazil has seen a considerable reduction in domestic production and the consequent increase in fertilizer imports in the last 10 years (OLIVEIRA; MALAGOLLI; CELLA, 2019). This shows that Brazil relies heavily on fertilizer imports to meet its needs. Increased plant diversity in agricultural systems promotes the provision of ecosystem services that ensure food, energy, water quality and nutrient cycling (FINNEY; WHITE; KAYE, 2016)

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