Response of Wheat-Maize Cropping Sequence in a Calcareous Soil to Some Mineral or Chelated Micronutrient Forms Added to Soil in Combination With Sulphur and Organic Manures

Abstract

The current work aimed to evaluate the effect of some micronutrients (Fe, Mn, Zn and Cu) in mineral (sulphates) and chelated (-amino acids and -EDTA) forms added to soil in solely or in combined treatments with both organic composts (wheat residues and cattle wastes) and sulphur on grain and straw yields as well as their contents of such micronutrients for wheat-maize cropping sequence in a calcareous soil, with special reference to the effects of these treatments on available soil contents of these micronutrients. To achieve this target two field experiments were conducted on a calcareous soil located at the eastern edge of Tamia district, El Fayoum Governorate, and cultivated with winter wheat (Sakha 69) followed by summer maize (single cross 10 hybrid) to verify the results obtained during growing season of 2003/2004 under surface irrigation system.The data obtained reveal that the experimental soil is characterized by secondary calcic formations in compacted phase, especially in the uppermost layer, and micronutrient deficient. The soil is classified at the family level as Typic Haplocalcids, clayey, mixed, hyperthermic. Also, its capability was evaluated as marginally suitable (S3ws), with a moderate intensity degree (rating = 60-85) for all the identified soil limitations (wetness, soil texture, soil depth and CaCO 3 content). The results showed an improvement occurred in available micronutrient contents (Fe, Mn, Zn and Cu) in the studied soil as a result of the applied treatments, with different magnitudes depend on their effective roles, nature of chemical composition, as shown in the following descending order: mineral micronutrients + organic composts > micronutrients + sulphur > chelated micronutrients > organic composts + sulphur > mineral micronutrients > organic composts > sulphur.The favourable conditions of the combined treatments with organic composts or sulphur are commonly achieved by lowering soil pH and forming organo-metalic compounds. The chelated micronutrients (-amino acids and -EDTA) represented the next superior form due to a higher portion of these compounds still in maintained active forms for uptake by plant roots.The beneficial effects of the studied treatments were actually reflected on increasing the grain and straw yields of wheat and also extended to the next cultivated maize. In addition, the positive effects of the studied treatments are more attributed to improve the efficiency of micronutrients uptake according to their effective roles. Moreover, the micronutrients response of Fe, Mn, Zn and Cu to accumulate in the grain and straw tissues showed a closely relationship to their corresponding available contents in the treated soils.