الفهرس 
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Abstract
Two field experiments were conducted at Sakha Agricultural Research Station Farm, Kafr El-Sheikh Governorate during growing seasons (2004/2005 and 2005) to study the impact of application of compost (zero and 20 m3 fed-1), elemental sulphur (zero, 450 and 900 kg fed-1) and N P mineral fertilizers rates (50, 75 and 100% from the recommended dose). On mobility of nitrogen and phosphorus in soil, availability of N, P in soil, some soil properties, yield and its components of wheat (variety Giza 168) and soybean (variety Giza 23) crops and the relationship between the residual amount of N and P in different soil depths and the rate of N and P application. The experimental design was split-split plot design with three replicates, where the main plots were assigned to compost rates, the sub-plots were devoted to sulphur rates and N P mineral fertilizers were allocated in sub-sub plots. Results revealed that total nitrogen, total phosphorus, available nitrogen, available phosphorus, available potassium and sulphur concentration were increased due to interaction between the application of 20 m3 compost fed-1, 900 kg sulphur fed-1 and N, P fertilizers at a rate of 100% from the recommended dose. Total CaCO and bulk density values were slightly decreased under application of compost, sulphur and N, P mineral fertilizers at higher rates. On contrary, the highest values of soil porosity, soil organic matter and basic infiltration rate were obtained with interaction between the abovementioned treatments. The interaction between application of 20 m3 compost fed-1, 900 kg sulphur fed-1and 100% N P mineral fertilizers from the recommended dose achieved the highest values of 1000 grain and 100 seed weight, grain yield and straw yield for wheat and soybean. Also, the interaction between the abovementioned gaves the highest values of protein content in grain and seeds of both crops and achieved the highest oil percentage in seeds of soybean. The application of 20 m3 compost fed-1, 900 kg sulphur fed-1 and 100% N P mineral from the recommended dose increased nitrogen percentage and its uptake, phosphorus percentage and its uptake, potassium percentage and its uptake and sulphur concentration and its uptake in grains and straw of wheat and seeds and straw of soybean. Expected mineralized N was increased with application of 20 m3 compost fed-1, 900 kg sulphur fed-1and nitrogen mineral fertilizer at a rate of 75 or 100% from the recommended dose. Residual available N concentration was increased with addition of 20 m3 compost fed-1 900 kg sulphur fed-1 and 100% N fertilizer from the recommended dose. The expected N losses % from the soil decreased with addition of compost, also addition of sulphur up to 900 kg fed-1decreased N losses, while the application of N P fertilizers at a rate of 100% from the recommended dose increased the N losses %. The highest values for residual available P were obtained by application of 20 m3 compost fed-1, 900 kg sulphur fed-1 and 100% N P fertilizers from the recommended dos. The unavailable P-residual decreased with addition of 20 m2 compost fed-1, 900 kg sulphur fed-1, while the application of 100% N P fertilizers from the recommended dose increased the unavailable-P.