Improvement of loamy sand soil and potato plant productivity under integrated organic and inorganic nitrogen fertilizers

Two experiments were conducted at EL Khattatba region – Egypt during two winter seasons to evaluate the effect of single or combined application of organic nitrogen fertilizer farmyard manure, chicken manure and compost with inorganic nitrogen fertilizer (ammonium nitrate 33.5%) on soil properties and identify the best rates on potato tuber yield and quality. Five ratio of nitrogen fertilizers were 100% nitrogen mineral fertilizer, 75% nitrogen mineral+25% nitrogen organic fertilizer, 50% nitrogen mineral +50% nitrogen organic fertilizer, 25%nitrogen mineral + 75% nitrogen organic fertilizer and 100% nitrogen organic fertilizer. Organic carbon content was increased significantly with applied organic fertilizers compared to mineral fertilizer. Soil total nitrogen ascertained highest values by applying mineral N fertilizer than organic fertilizer treatments. C: N ratio of soil significantly increased with organic fertilizers and 100%N organic fertilizer treatment was superiority for raising C:N ratio of soil. 100% N mineral fertilizer treatment had depressive effects on C: N which were lower than tested soil. Both pH and bulk density were significantly decreased by applying organic fertilizers. 100% N chicken manure treatment was recorded maximum decreasing. Each of E.C, Kh and available water were influenced by applying organic fertilizers types. 100%N organic fertilizers were ascertained the significant effect for each EC, Kh and available water compared to other rates or 100%N mineral fertilizer. The highest tuber yield was ascertained by applying the treatment 25%N organic fertilizer with 75% N mineral for each season. Carbohydrate% was decreased with raising the rates of organic fertilizers and the maximum values were recorded at 100%N mineral. There was irregular trend for tuber specific gravity with organic fertilizers or their rates for both seasons. The relation between NO3-N ion, N% content in tuber and Total N% in soil indicated that increasing ratio of organic fertilizers decreased the NO3-N ion in tuber.