Drainage water quality evaluation by fertilizing fields with manure from large livestock enterprises

Abstract

The research was conducted during the years 2008-2012 in the drained fields fertilized by stockbreeding farms‘ manure, where 2 variants were installed: fertilized and unfertilized fields. The field was fertilized with manure every spring, in which according to the fertilizing value of manure, the following contents of total nitrogen passed into manure-fertilized fields in each year: 2008 – 169 kg ha-1, 2009 – 168 kg ha-1; 2010 – 169 kg ha-1, 2011 – 169 kg ha-1, 2012 – 170 kg ha-1. Maize for cattle forage was grown in experimental fields. The soil of the research subject is sandy loam. In the layer 0-40 cm of the fertilized area, the humus content in the soil fluctuated from low (1.2 %) to high (4.9 %). The content of mineral nitrogen fluctuated from 14.2 to 289 kg ha-1 what corresponded to the nitrogen content very low and very high respectively. The content of humus in non-fertilized soil fluctuated from the very low value (1 %) to moderate value (3 %). The content of mineral nitrogen fluctuated from 10.9 to 130 kg ha-1, what corresponded to the nitrogen content very low and very high. For the purpose of chemical investigations, water samples from drainage were taken once per month. Water analyses were carried out by the accredited Chemical Analytical Laboratory of the Water Management Engineering Institute of Aleksandras Stulginskis University. Ntotal in drainage water was determined by applying the spectrometric method, by mineralizing with potassium persulphate. Soil samples for agrochemical investigations were taken monthly from the depth of 0-60 cm at every 20 cm. To identify the content of nitrogen in the soil, the following research methods were applied: ammonium nitrogen (N-NH4 +) – colorimetric with Nessler’s reagent in KCl extract; nitrate nitrogen (N-NO3 -) — potentiometric with selective electrode. Analyses of N – NH4 + and N – NO3 - were carried out by means of analyser “FIA Star 5012”