Abstract
Lack of response by Stylosanthes hamata cv Verano to P applications prompted further trials to ascertain other nutrient problems in a ferruginous soil in the subhumid zone of Nigeria. Use of the subtractive technique in one trial showed that stylo DM yield from -Cu or -P treatments was only 35% of the yield achieved when all nutrients were supplied. More nutrient deficiencies such as S, Mo and Zn surfaced when DM productivity was followed through the second year without further nutrient additions or carry-over of herbage from the previous year. Herbage nutrient composition of stylo was variable. The level of Zn in all treatments but one ranged between 0.48 to 9.75 ppm which appears to be very much below the critical limit required for plants and animals. Significant interaction between P and Cu in terms of DM yield was also observed in another factorial experiment. As these experiments were only pointers to soil-related constraints for Verano stylo and possibly other forage crops, there is an urgent need for more systematic soil fertility and animal nutrient supplementation studies.
