POTATO PRODUCTION BY ORGANIC FARMING 1. ROLE OF ORGANIC FERTILIZER AND WHEY ON SOIL PHYSICAL PROPERTIES AND MICROORGANISM NUMBER

Abstract

A field experiment was carried out at the College of Agric. Abu - Ghraib in silt clay loam (in spring season) and silt clay soil (in autumn season) in 2006 to examine the effect of cow manure (0,10 and 20% WAV), poultry residues 0 , 10% and 20% and mixing whey with irrigation water at 0 , 10% and 20% in randomized complete block design with three replicates on soil physical properties and soil microorganism numbers. The control treatment represented the application of chemical fertilizer as recommended (1000 kg/ha of NPK 27:27:0). Soil samples to 30 cm deep were collected at periods of 30 , 60 and 90 days after tuber planting . Results showed that application of organic fertilizer at 20% regardless its source with the use of 20% whey increased soil viscosity 5.00 , 4.87 , 3.98 and 3.76 m. poise and mean weight diameters 7.98 , 7.49 , 5.23 and 4.14 mm for cow manure and poultry residues for two seasons , 90 days after planting, respectively . Soil aggregates greater than 5 cm in diameter were also increased from 98.08 and 95.52% for control treatment to 100% for other treatments. Organic fertilizer and whey application increased numbers of bacteria, fungi and actinomyces . A new mechanism for soil aggregation resulted from organic matter and whey application was suggested.