Integrated Effects of Bio and Mineral Fertilizers and Humic Substances on Growth, Yield and Nutrient Contents of Fertigated Cowpea ( Vigna unguiculata L.) Grown on Sandy Soils

摘要

A bio-fertigation trial was conducted at the experimental farm of National Research Centre, Noubaria, Egypt during May to August of 2010 to study the relative efficacy of bio-fertigation of liquid formulation of N-fixer ( Azospirillum sp. and Azotobacter sp.) and P-solubilizer ( Basillus megatherium ) and humic substances (HS) and inorganic fertilizers injected through drip irrigation system on soil properties and growth and yield of cowpea plant. Four treatments were utilized mainly, basal control treatment at 100% recommended dose of NPK as drip fertigation while 50% recommended dose of NPK as drip fertigation combined with bio fertigation of microbial inoculums and/or Humic Substances (HS) were injected through drip irrigation system. Application of 50% recommended dose of NPK with bio fertigation and humic substances improved nutrient contents in soil (N, P, K, Fe, Mn and Zn), plant growth, nodule parameters, seed quality and fertilizer use efficiency and nutritional assimilation of cowpea followed by 100% recommended dose of NPK, 50% recommended dose of NPK jointly with humic substances and then 50% recommended dose of NPK in combination with bio fertigation treatments. In spite of 100% recommended NPK drip fertigation improved cowpea yield solely, application of 50% recommended NPK dose in conjunction with bio fertigation and humic substances gave rather equal yield. Injection of 50% recommended dose NPK as drip fertigation in combination with biofertigation of liquid formulation and humic substances was better and comparable way than the other treatments. Bio fertigation of microbial inoculums and humic substances could be used as a complementary for mineral fertilizers to improve yield and quality of cowpea under sandy soil conditions which protect the environment chemical pollution and its harmful effect on human and animal health.