Field experiments were conducted on clay loam soil during the two successive seasons, summer season 2017 using maize plants (Zea mays L.) and winter season (2017/2018) using barley plants (Hordum vulgare L.) at El-Gemmeiza Agricultural Research Station, El-Gharbia Governorate to evaluate the direct and residual effects of compost rates placed in 30 cm moles depth, arranged in parallel orientation with respect to one another and spaced at 3 m apart or placed on the surface soil layers besides the nitrogen fertilizer rates on availability of some soil macro and micronutrients and chemical composition of maize and barley plants, also the productivity of yield and yield components.
The rates of compost were 0.0, 2.5, 5.0 and 7.5 ton fed.^-1, while the nitrogen rates were 0.0, 50, 75 and 100 % of the recommended dose for every growing crop. The experiments were conducted in split-split plot in a randomized complete block design (RCBD) with three replicates.
All different treatments led to markedly increases in available NPK in the two growing seasons. Soil extractable metals (Fe, Zn, Mn and Cu) were increased with all treatments in the two growing seasons. Concentration and uptake of macronutrients (N, P, and K) and micronutrients (Fe, Zn, Mn and Cu) in maize and barley grains and straw were increased with all different treatments in the two seasons. The yield and yield components of maize and barley positively responded to all treatments. Generally, it could be concluded that, the highest values of yield and its components for maize and barley plants were obtained by the addition of 7.5-ton compost fed^-1 in 30 cm mole depth with 100% of the recommended dose for nitrogen fertilizer and get a markedly improvement in availability of macro and micronutrients to the plants. The highest grain yield of maize plants increased to 3.3787 ton fed^-1, also the highest grain and straw yields of barley plants increased to 2.9327 and 4.2013 ton fed^-1, respectively. Accumulation of micronutrients in plant biomass was within the normal range and did not produce depressing effects on crop yields