Carbon and Nitrogen Stocks and Soil Quality in an Area Cultivated with Guinea Grass under the Residual Effect of Nitrogen Doses

Antonio Leandro Chaves Gurgel,Manoel Gustavo Paranhos Da Silva,Gelson Dos Santos Difante,Valeria Pacheco Batista Euclides,Alexandre Romeiro De Araujo,Denise Baptaglin Montagner

doi:10.3390/su12229381

Antonio Leandro Chaves Gurgel, Manoel Gustavo Paranhos Da Silva + Show 4 more

Open Access

https://doi.org/10.3390/su12229381

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Abstract

This study examines the residual effect of nitrogen (N) doses on the carbon (C) and N stocks and on soil quality in an area cultivated with guinea grass. The pastures received three annual doses of N (100, 200 and 300 kg ha−1) from 2015 to 2017. In 2018, N fertilization was not applied so the residual effect of the nutrient could be characterized. Soil chemical attributes, C and N stocks, density and penetration resistance and root system characteristics were evaluated at different depths. No difference was observed between the N doses for soil density, which averaged 1.22 and 1.25 g cm−3 under and between the tussocks of guinea grass, respectively. Penetration resistance was affected by the N doses post-grazing, with the highest value (1.9 MPa) observed in pastures that received 300 kg ha−1 of N for three consecutive years. Root dry mass was not affected by the N doses. There was no effect of N doses on the average (19.7 mg ha−1) or total (134.3 mg ha−1) C stock in the soil. The total N stock did not change (11.3 mg ha−1) in response to the N doses; however, the average N stock was higher in the soil cultivated with guinea grass under the N dose of 300 kg ha−1 (1.7 mg ha−1). The N doses had little interference with the soil chemical and physical aspects. Regardless of the dose, high C and N stocks were observed in the soil cultivated with guinea grass. Therefore, when properly managed, intensive pasture-based animal production systems become important allies of the environment.

Highlights

In addition to holding the largest commercial cattle herd in the world, Brazil is the largest exporter of beef [1]
The doses affected the levels of exchangeable magnesium (p = 0.0229); the highest concentrations in the soil were found using the N doses of 100 and 200 kg ha−1 and for organic matter content (p = 0.0046), the highest values in the soil occurred under the N doses of 200 and 300 kg ha−1 (Figure 2)
Few changes were observed in the chemical attributes of soil in response to the N doses, which was likely due to the similar maintenance fertilization management adopted in the years preceding data collection

Summary

Introduction

In addition to holding the largest commercial cattle herd in the world, Brazil is the largest exporter of beef [1]. The main factor making beef cattle a competitive activity worldwide is its production being carried out almost exclusively on pasture. Nitrogen (N) fertilization, coupled with maintenance fertilization with other nutrients essential to plants, is essential to ensure agricultural productivity [4,5,6,7]. In this respect, one of the main triggers of the pasture degradation process is low adoption of these technologies associated with inadequate management of pasture and grazing. The use of N increases and allows the intensification of the use of primary productivity through a higher stocking rate [8]. The pressure exerted by animal trampling can compromise the physical characteristics of the soil as a result of increased soil density (SD) and penetration resistance (PR) and reduced porosity [11,12]

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Conclusion