Organic amendments can enhance soil fertility and productivity,
improving the plant nutrient status for potentially limiting
nutrients such as N, P and K as well as for several micronutrients
(Liu et al., 2009). In this respect, positive correlations were found
in our experiment between watermelon yield and fruit nutrient
concentration (N and K at P < 0.01), and between the mean fruit
weight and both fruit N concentration (P < 0.05) and fruit P concentration
(P < 0.01). Likewise, the marketable yield of cauliflower
was correlated significantly with both leaf N and P (P < 0.01) and K
(P < 0.05); these results highlight the great impact of plant nutrient
status on crop production.