Influence of growing plants and nitrogen fertilizer on saturated hydraulicconductivity

A field experiment was conducted on a sandy loam (typic Hapludoll) to test the effect of maize (Zea mays L.) and nitrogen (N) fertilizers on soil satu rated hydraulic conductivity (Ksat). Half of the plots were planted to maiz e and the other half were kept unplanted. All the plots were fertilized at the rate of 75 kg ha(-1), with two fertilizers differing in their acidity i ndex [calcium ammonium nitrate (CAN)=16 and ammonium sulphate (AS)=111]. Un disturbed topsoil samples were taken at the time of maize harvest to determ ine soil Ksat in the laboratory. Total organic carbon (TOC) and soluble car bon (SC), pH (1:2.5), and the electrical conductivity (EC) of soil saturate d extract were determined in grounded and sieved soil samples. The Ksat rea ched the highest values under maize fertilized with AS. Most of the variati on of soil Ksat was determined by the increment of soil salinity. So, soil permeability improvements were caused by a greater flocculation of soil col loids because of saline effects. Soil pH decrease caused by these acid N so urces did not provoke the dissolution of organic matter because none of the carbon (C)-forms measured in the experiment were affected by the fertiliza tion. Thus, other C-compounds different from those here measured might be i mproving soil permeability.