Resumo

FLORES MARGEZ, Juan Pedro et al. Soil texture and type of irrigation water on phosphorus availability from cow manure. Terra Latinoam [online]. 2013, vol.31, n.3, pp.211-220. ISSN 2395-8030.

There is little information relative to mineralization of macronutrients, such as phosphorus, in agricultural soils amended with manure and irrigated with sewage water. Soil variability and management systems as well as the type of water existing in the Valle de Juarez, Chihuahua, are factors that have significant effect on manure mineralization. The objective of this study was to determine the amount of phosphorus from dairy manure mineralized in three soils irrigated with two types of water under field conditions. The experiment was conducted at the Biomedical Sciences Institute of the Universidad Autónoma de Ciudad Juarez, from March to September 2010. The factors studied were three textural types of soils: sandy loam, loam, and clay; two type of water: treated sewage water from the main water treatment plant at Ciudad Juarez and tap water; and two manure rates: 0 and 50 Mg ha-1 dry weight base. The experimental units were 5 × 15 cm aluminum cylinders. The experimental design was completely randomized with a factorial arrangement, and 12 treatments with four replications. Electric conductivity increased significantly in soils as a result of manure application from 3.11 to 3.77 dS m-1; soil moisture increased from 5.09 to 6.52% at the end of the experiment as an effect of manure application. There was no effect of wastewater on P mineralization. The amount of P Olsen detected in soils at the end of the experiment after 193 days of incubation were 40.8, 54.4, and 30.5 mg kg-1 for the clay, loam, and sandy loam soils, respectively. The net amounts of mineralized P Olsen were 17.4, 24.4, and 18.7 mg kg1for the same soils, and P available for plants was 78.8, 87.5, and 84.5 kg ha-1. The results of this study demonstrate that manure application and soil type affect the availability of P Olsen, but not the type of water. This should be considered in soil management to improve the use of manure as organic fertilizer in areas where treated wastewater is being increasingly used for irrigation due to low availability of fresh water.

Palavras-chave : organic matter decomposition; mineralization; salinity; wastewater.