Soil–Plant Nutrient Relationship at Different Growth Stages of Spinach as Affected by Phosphorus and Manure Applications

Abstract

A greenhouse experiment was conducted to study the soil–plant phosphorus (P) correlation at different growth stages of spinach (Spinacia oleracea L.). Treatments consisted of three levels of phosphorus [0 20, and 60 mg kg−1 as Ca(H2PO4)2] and two levels of organic matter (0% and 2% w/w as feedlot cattle manure). Plant and soil samples were taken at 4, 5, 6, 7, and 8 weeks after seedling emergence and were analyzed for plant nutrients. Results showed that correlation between soil and plant P concentration was significant and positive at the 4th week but significant and negative later on. Plant P concentration was the greatest at the 4th week. During all growth stages, dry-matter yield of plant increased with increase in soil P concentration, suggesting the importance of maintaining adequate levels of phosphorus in soil, especially during the early stages of growth. Application of organic matter significantly increased soil and plant P concentrations.