Pig slurry in carpet grass pasture: Yield and plant-available nitrogen

Dejeto líquido de suínos em pastagem de grama-tapete: Produção e nitrogênio disponibilizado

ABSTRACT

This study evaluated the response of carpet grass to pig slurry fertilization in order to estimate the agronomic efficiency and the plant-available nitrogen (N) of such manure. A field test was conducted during two years, following a randomized block design with six replicates of the treatments: 0, 100, 200, 300, 400 and 500 kg N ha^-1 year^-1, which resulted in 0, 60, 120, 180, 240 and 300 m³ ha^-1 (2008/09), and 0, 42, 84, 126, 168 and 210 m³ ha^-1 (2009/10), according to the N content of the pig slurry used in each year. These treatments were compared with ammonium nitrate (200 kg N ha^-1 year^-1), in order to estimate the plant-available nitrogen of the manure for the pasture. Pig slurry doses increased linearly the dry matter yield. In 2008/2009, it was increased from 2,600 (0 kg N ha^-1) to 7,718 kg ha^-1 (500 kg N ha^-1), while in 2009-2010 it ranged from 4,310 (0 kg N ha^-1) to 12,321 kg ha^-1 (500 kg N ha^-1). The average agronomic efficiency of the manurewas 15 kg DM kg^-1 N and it was lower than that found with ammonium nitrate (27 kg DM kg^-1 N).The estimated plant-available N of the pig slurry was similar between the growing years. The N fraction of this manure available to the pasture was 0.64 (2008-09) and 0.60 (2009-10).

Key words:
Axonopus affinis; agronomic nitrogen efficiency; nitrogen efficiency index; manure; perennial pasture