Long-term nitrogen fertilization in native pasture with Italian ryegrass introduction - Effects on soil health attribute indicators

Abstract

Native pastures are of great importance for cattle and sheep nutrition in the Pampa biome. However, due to its low productivity, the Italian ryegrass introduction and the nitrogen (N) fertilization are alternatives proposed to intensify livestock production in a sustainable manner. The objective of this study was to evaluate the effects of long-term N application on soil health indicators in a native pasture with Italian ryegrass introduction in southern Brazil. The experiment consists of a secondary native pasture under continuous grazing and constant herbage allowance. In 1996 experimental area was broadcast limed and the experiment was initiated, testing three N topdressing rates (0, 100 and 200kg N ha-1 year-1). In 2010 soil of experimental and reference area of non grazed native grassland was sampled in the soil layers of 0-20 and 20-40cm. Total, particulate and mineral associated carbon (C) and N stocks were evaluated. Soil microbiological attributes were evaluated in 0-5 and 5-10cm soil layers. The long-term N fertilization in soils with native pasture and Italian ryegrass introduction did not affect total C and N stocks. However, increases in N particulate fraction were seen with 100kg ha-1 year-1 of N rate of fertilization. Furthermore, the increase in N rates increased N microbial biomass and respiration.

Revisiting the past to understand the present and future of soil health in Brazil

“…As in the Amazon and other biomes, the Pampa has suffered severe fragmentation due to its widespread use for livestock production, reflecting effects on soil health indicators, such as microbial diversity, carbon and nitrogen stocks (123), and soil structure and aggregates (124). Thus, visible efforts were necessary to find a set of in-field indicators capable of monitoring changes in soil biological functioning that can be used to establish agricultural policies and design new strategies of cropping system management (125).…”

Ruminal degradation and fermentation kinetics of the Mulato II grass (Convert HD364) under different sources of nitrogen fertilization

“…Within this context, the dosage and source of fertilization will depend on factors such as soil quality and animal load on the pasture. This is essential for soil conservation and promoting better performance for both the forage species and ruminants (3)(4)(5) .…”

Degradação ruminal e cinética de fermentação do capim Mulato II (Convert HD364) sob diferentes fontes de adubação nitrogenada

“…Esta estratégia, além de aumentar a produção de forragem, aliada a um manejo adequado, é fundamental para garantir a fertilidade e conservação do solo. Nesse contexto, a dose e a fonte de adubação dependerão de fatores como a análise do solo e a lotação animal a que a pastagem será submetida, sendo fundamentais para a conservação do solo e para promover um melhor desempenho das espécies forrageiras e de bovinos (3)(4)(5) .…”