Abstract
Cowpea (Vigna unguiculata) is an essential legume crop widely cultivated in arid and semi-arid
regions due to its adaptability to low soil fertility. However, phosphorus deficiency remains a
major constraint to its optimal growth. This study investigates the impact of rock phosphate (RP)
application levels, placement methods, and cowpea variety selection on growth parameters in
Sokoto during the 2024 cropping season. A randomized complete block design (RCBD) was used
with two cowpea varieties (Sampea-7 and Baadare), three RP levels (25, 50, and 75 kg ha?), and
three placement methods (plough-sole, broadcast, and side-band). Results showed that increasing
RP levels improved canopy height, leaf number, and canopy spread, with 75 kg RP ha? yielding
the highest vegetative growth. The plough-sole placement method enhanced nutrient uptake,
resulting in superior growth parameters compared to broadcast and side-band methods.
Additionally, Baadare exhibited better canopy height, while Sampea-7 displayed wider canopy
spread and earlier maturity. These findings highlight the importance of optimizing phosphorus
application strategies to improve cowpea productivity in phosphorus-deficient soils.
References
Bationo, A., Fening, J. O., & Kwaw, A. (2018). Assessment of soil fertility status and integrated
soil fertility management in Ghana. Improving the Profitability, Sustainability and
Efficiency of Nutrients Through Site Specific Fertilizer Recommendations in West Africa
Agro-Ecosystems: Volume 1, 93-138.
Chien, S. H., & Menon, R. G. (1995). Factors affecting the agronomic effectiveness of phosphate
rock for direct application. Fertilizer research, 41, 227-234.
Chien, S. H., Prochnow, L. I., Tu, S., & Snyder, C. S. (2011). Agronomic and environmental
aspects of phosphate fertilizers varying in source and solubility: an update review. Nutrient
Cycling in Agroecosystems, 89(2), 229-255.
Freiling, M., von Tucher, S., & Schmidhalter, U. (2022). Factors influencing phosphorus
placement and effects on yield and yield parameters: A meta-analysis. Soil and Tillage
Research, 216, 105257.
Ehlers, J. D., & Hall, A. E. (1997). Cowpea (Vigna unguiculata L. walp.). Field crops
research, 53(1-3), 187-204.
Holford, I. C. R. (1997). Soil phosphorus: its measurement, and its uptake by plants. Soil
Research, 35(2), 227-240.
Marschner, H. (2012). Mineral nutrition of higher plants. Academic press.
Masuda, T., & Goldsmith, P. D. (2009). World soybean markets: Structure, performance and
policy. World Soybean Research Conference.
Rao, J. K., Dart, P. J., & Sastry, P. V. S. S. (1983). Residual effect of pigeonpea (Cajanus cajan)
on yield and nitrogen response of maize. Experimental Agriculture, 19(2), 131-141.
Singh, S. K., Pathak, R., & Pancholy, A. (2017). Role of root nodule bacteria in improving soil
fertility and growth attributes of leguminous plants under arid and semiarid
environments. Rhizobium Biology and Biotechnology, 39-60.
Taiz, L., Zeiger, E., Møller, I. M., & Murphy, A. (2015). Plant physiology and development.
Sinauer Associates.
Zapata, F., & Roy, R. N. (2004). Use of phosphate rocks for sustainable agriculture. Food and
Agriculture Organization of the United Nations.
