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□ Nutrient deficiency in maize (Zea maysL.) was assessed through critical value methods (CVM) and the Diagnosis and Recommendation Integrated System (DRIS) to compare mean yield, foliar nutrient status, and variance of nutrients in low-and high-yielding groups. A two year (2001 and 2002) field experiment was set in Benin. Based on DRIS, the most limiting nutrients in 2001 were phosphorus (P) followed by sulfur (S), potassium (K), and zinc (Zn), whereas in 2002, it was manganese (Mn), followed by Zn and magnesium (Mg). However, based on the CVM, nitrogen (N) and S were deficient in both years. Calcium (Ca) was deficient in 2002 and adequate in 2001. Leaf P and K concentrations were adequate in 2002 both in high and low yielding populations based on DRIS and CVM. Standard nutrient levels and DRIS norms established for maize can be used to evaluate crop nutritional status and correct nutritional imbalances. [ABSTRACT FROM AUTHOR]

The objective of the study carried out in the Upper Oueme Catchment in Benin (West Africa) was to assess the nutrient status in yam (Dioscorea rotundata) through the Diagnostic and Recommendation Integrated System (DRIS), to compare yield, foliar nutrient concentrations and the variance of nutrients of low-and high-yielding groups. Field experiments were carried out in 2001 and 2002 using a randomized complete block design with four treatments, 2001: n = 80, 2002: n = 109) at three sites: Beterou, Dogue, and Wewe. Nitrogen (N), followed by potassium (K), phosphorus (P), and magnesium (Mg) were identified as the most limiting nutrients in 2001 whereas sulfur (S) followed by N was identified as most limiting ones in 2002. Imbalanced nutrition was observed in both the years but was higher in 2001 compared in 2002. They may be utilized as a basis for calibrating the fertilization program of yam. [ABSTRACT FROM AUTHOR]