Nitrogen (N) deficiency is the most widely spread macro- nutrient fertility problem in the Northern Guinea Savanna (NGS). Correction of this disorder is usually through the soil application of solid N fertilizers and other N-carriers. The quantities of solid fertilizers required to meet the needs of cereal crops through this approach are usually high and cost ineffective. The fertilizers also undergo various transformation in the soil. There is therefore the need to identify another cost effective and more efficient method of supplying N to cereal crops. A field study was conducted at Samaru (l10111N and 07°381E) Latitude and Longitude respectively in the NGS agro-ecology in 1997 rainy and 1998 dry seasons to compare the agronomic effectiveness of soil. There were two experiments carried out in each season: a) Urea application by foliar spray b) Urea application via the soil The first trial tested the response of maize (TZESR-W) to five levels of N foliarly applied as 0,1,2,3 and 4% N ha-1 (0.00, 22.86, 45.72, 68.58 and 91.44 Kg N ha-1). The second trial tested the response of maize to 0, 40, 80, 120 and 160 KgN.ha-1 in the form of Urea applied via the soil. Results obtained indicated that 2% N ha-1 (folia applied) and 120 KgNha-1 via the soil produced the highest grain yields of 3921 and 5412 Kgha-1 and stover yields of 4936 and 7130 Kgha-1 respectively. And for the 1998 trials, highest grain yields of 1197 and 1713 Kgha-1 were obtained with 2% N ha-1 (foliar applied) and 120 Kgha-1 respectively. The corresponding stover yields were 304.3 and 4071 Kgha-1. There were 61.4% and 71.3% grain yields increased above the control for foliar and soil applied trials. The results also indicated that various soil properties, for examples, pH and organic carbon influenced the availability of N in the soils. Parameters such as grain, and stover yields, 50% tasseling and silking time, 1000 grain weight and leaf area were significantly (P=0.05) affected by foliar sprayed N in 1997 trial while only leaf area, 1000 grains weight, grain and stover yields were significantly (p=0.05) affected by soil applied N. Both methods of N application have significant effect on the nutrients (N, P and K) uptake. Uptake of these nutrients increased with increased N cone, up to 2% in the foliar trials, uptake decreased with further increased N cone, ha-1 to 3 and 4%. With soil applied N method, uptake of N, P and K increased with increased N rates from 0 – 120 KgNha-1. Uptake in stover did not show out particular trend in P and K uptake. Leaf area, number of cobs/plant, number of leaves/plant correlated positively with grain and stover yields. The economic analysis of 1997 rainfed trial gave good returns for producing one hectare of maize. The soil applied N trial gave a net return of N55,238 while the foliar trial gave a return of N37,545. For the dry season trials, water supplied to the fields was costed by using Hadejia-Jamare River Basin Authority charges and used for economic analysis. The results from the two seasons trials, clearly showed that foliar N fertilization cannot successfully substitute for soil N fertilization as a means of supplying N to cereal crops. However, it is recommended in situations where the cost of urea fertilizer is prohibitive. To further save cost, it can be applied in combination with insecticides and pesticides in a single spray.
THE RESPONSE OF MAIZE (Zea mays L.) TO SOIL AND FOLIAR APPLIED UREA IN NORTHERN GUINEA SAVANNA OF NIGERIA