EFFECT OF COMPOST AND POTASSIUM PHOSPHATE APPLICATIONS TO A CALCAREOUS SOIL CULTIVATED WITH VEGETABLE CROPS ROTATION ON THEIR PRODUCTION AND SOIL FERTILITY

A field experiment was carried out on a calcareous soil at Abou massou village (٤8 km south-west to Alexandria) with four vegetable crops cultivated in succession (garlic, , cauliflower and jews mallow) was conducted to investigate how application rates of plants residues trim farm operations compost and potassium phosphate, also, the vegetable dry matter their NPK uptake can affect the yield. The study also investigated the resultant effects on soil fertility. Irrigation was up to field capacity using canal water. Results indicated that soil salinity, soluble chlorides and sodium decreased sharply after garlic and gradually after that, while bicarbonates increased sharply during the first months and decreased gradually at a level higher than the start point. Sulphates, calcium, magnesium and potassium decreased over the time. Rates of compost application were without pronounced effect on total soluble salts or soluble cations and anions with the exception of bicarbonates. Rates of plants residues trim farm operations compost and potassium phosphate included also vegetable dry matter and their NPK uptake in addition to soil properties and vegetable yields through 20-months were also studied. Results indicate that each of the use compost rates were effective in increasing dry matter, N and P uptake by the three vegetable crops over the control. The same trend was noticed also at the phosphate and potassium treatments. It may be concluded that vegetable crop production in calcareous soil depend on the direct and residual effect of organic and mineral N and P fertilization for 20 months period and K fertilization for about three quarters of this period. Also, the compost application might improve the soil properties while the addition of phosphorus and potassium enhances the availability of nutrients in the soil throughout the cropping period.