African Journal of Biotechnology
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African Journal of Biotechnology Vol. 2 (10), pp. 345-349, October 2003 ISSN 1684–5315 © 2003 Academic Journals
Influence of nitrogen, phosphorus and potassium
application on the yield of maize in the savanna zone of Nigeria Kogbe J. O. S. and Adediran J. A.* Institute of Agricultural Research and Training, Obafemi Awolowo University, PMB 5029, Ibadan, Nigeria *Corresponding author:E-mail: jadediran@yahoo.co.uk. Accepted 31 August 2003
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Field trials testing the effects of five rates each of N, P and K application on three hybrid and two open-pollinated maize varieties were conducted in three separate experiments on an Arenic haplustalf (USDA) at Ilora in the derived savanna and Typic paleustalf (USDA) at Mokwa in the southern guinea savanna of Nigeria. The hybrid maize varieties planted were 8516-12, 8321-18 and 8329-15 and were compared with the open-pollinated maize, TZSR-Y and TZSR-W. Nitrogen was applied at rates 0-200 kg ha-1 in the first trial, while P and K were supplied as basal nutrients. In the second trial, P was applied at rates 0- 80 kg P2O5 ha-1 using basal N and K fertilizers. In another trial, K was applied at rates 0-120 kg ha-1 with blanket application of N and P. The hybrid maize gave higher yields and used N and P more efficiently than the open pollinated at both trial locations. The yield of maize was higher in the southern guinea savanna than in the derived savanna. The performance of the hybrid varieties followed in the ascending order of 8516-12, 8321-18 and 8329-15. The optimum rates of N and P for maize grown in the derived savanna were 100 and 40 kg ha-1respectively. In the southern guinea savanna the open pollinated and hybrid varieties responded up to 150 and 200 kg N ha-1 respectively. The 8516-12 showed higher N and P use efficiency than other varieties. Consequently, planting such variety could be advantageous, using minimal dose of fertilizer most especially, where farmers have less access to fertilizer. Key words: Hybrid maize, open pollinated maize, nitrogen use efficiency, phosphorus use efficiency.
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Maize production has become very popular and the crop is widely grown in many countries in the world. In recent times, production of hybrid maize has been given wide publicity among maize farmers in Nigeria. However, hybrid maize is well known for its high demand for plant nutrients and other production inputs. The farmer has been indoctrinated with the belief that all conditions required for maximum performance of hybrid maize have to be fulfilled to letters before the desired economic returns can be obtained. This extra production cost discourages most farmers engaging in hybrid maize production in the country. The yield of maize however, varies from variety to variety, location to location and also depends on the availability of essential factors such as soil nutrient status and application of fertilizers. Nitrogen is a vital plant nutrient and a major yield-determining factor required for maize production (Adediran and Banjoko, 1995; Shanti et al., 1997). Its availability in sufficient quantity throughout the growing season is essential for optimum maize growth. Most farmers in developing countries usually rely on the natural soil fertility for crop production. Opening up of a long fallow land may provide adequate nutrient to food crop. But cropping of such land is only successful within few years after opening of the fallowed land. Afterwards, subsequent cropping requires additional fertilizer input, most importantly that of nitrogen to maintain good yields. Phosphorus (P) is another limiting nutrient in maize production. Various factors could be responsible for P availability to crop plants. These include the form of native soil P, the type of P applied to the soil, and soil reaction. It has been reported that total P was higher in forest soils than in the savanna (Adepetu, 1970; Adepetu and Corey, 1975). Also, agricultural crops show different response to P fertilization. The results of various fertilizer experiments carried out in Nigeria have led to fertilizer recommendations that gave blanket nutrient requirements for maize in ecologies having varying soil conditions and under varying levels of soil management (FPDD, 1990). This practice is aimed at giving farmers a fairly appreciable economic return from the fertilizer input. For example, hybrid maize cultivation was found to require high fertilizer rate for optimum yield. Findings from these research work indicated, that maize responded to nitrogen better in the savanna than in the forest ecology (Sobulo, 1980). It was further suggested, that 60-70 kg N ha-1 served as economic rate for maize in the rainforest, and over 100 kg N ha-1 in the savanna. The difference between the two zones was, however, attributed to the presence of higher insulation in the savanna (Sobulo, 1980). Some work earlier carried out with phosphorus fertilizer indicated positive response of maize to low rates of P (Amon, 1965; Amon and Adetunji, 1970). Application of high rate was reported to be capable of causing nutrient imbalance and consequently yield depression of western yellow maize (Osiname, 1979).
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Field trials were carried out at Ilora in the derived savanna (savanna-forest mosaic) and at Mokwa in the southern guinea savanna of Nigeria for three years. The soil at Ilora was classified as Arenic haplustalf (United State Department of Agriculture, USDA) and that at Mokwa was Typic paleustalf (USDA). Soils at the trial sites were loamy sand Alfisol with moderate pH values. The exception was the sandy loam texture at Ilora and Mokwa observed on the potassium and nitrogen experimental sites, respectively. The sites in both locations had been under cultivation for three to four years before establishing the trials and the soils therefore showed low nutrient status, with the exception of K, which was generally adequate (Table 1).
Table 1. Selected physical and chemical characteristics of the soil before cropping of maize.
The hybrid maize (HBM) varieties planted were 8321-18, 8516-12, and 8329-15, which were recently introduced and have become popular in the zones of the experiments. Two open pollinated (OP) varieties (TZSR-W and TZSR-Y) commonly grown in the zones of the experiments were also planted for comparison. In the first trial, nitrogen fertilizer in the form of granular urea was applied to maize at 0, 50, 100, 150 and 200 kg N ha-1 two weeks after planting using drilling method. Phosphorus and potassium were applied at 40 kg P205 and 60 kg K20ha-1 as basal fertilizers. In the second trial, P was applied at rates 0, 20, 40, 60 and 80 kg P2O5 ha-1 while, N and K were supplied as basal fertilizers at 100 kg and 60 kg K2O ha-1, respectively. Whereas in the third trial, K application was done at 0, 30, 60, 90 and 120 kg K20 ha-1 using urea and single super phosphate at 100 kg N and 40 kg P2O5 ha-1, respectively as basal fertilizers. For all the trials, the control consists of treatment with only basal fertilizer application. Nitrogen (NUE) or phosphorus use efficiency (PUE) was calculated as the yield obtained from the N (Yn) or P (Yp) fertilized plot minus control (Yc), divided by a unit weight of the applied fertilizer (Nw for nitrogen and Pw for phosphorus): NUE =(Yn-Yc)/Nw PUE = (Yp-Yc)/Pw Soil samples were collected from the trial sites before cropping and were analyzed in the laboratory for selected physical and chemical properties. The plot size was 5.00 m X 5.25 m and planting space was 75 cm X 25 cm. The treatments were randomized within the block and replicated four times. Maize was harvested at maturity and grain yield was calculated at 12% moisture content. The data were subjected to analysis of variance and the means separation was performed by the Least Significant Difference (LSD) method utilizing the procedures of Gomez and Gomez (1984).
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Figure 1 shows the yield response of maize with respect to applied nitrogen rates. The yield of hybrid maize increased with rise in nitrogen rates at Ilora and Mokwa representing the derived savanna and southern guinea savanna respectively. At Ilora, the hybrid maize showed significant yield increase (p = 0.05) at rates above 100 kg N ha–1. On the other hand, application of 100 kg N ha-1 to open pollinated maize (OP) was not significantly different from using 150 kg N ha-1. The yield declined at rates above 100 kg Nha-1. Whereas, increased yield of hybrid maize (HBM) was observed at higher rates. The exception was for 8329-15, which showed a little yield decrease at these rates. Regardless of the maize varieties, the yield obtained from the southern guinea savanna was higher than from the derived savanna. For example, in the former location, application of 50 kg N ha-1 to both OP and HBM gave higher yield than applying up to 200 kg N ha-1 in the later.
Figure 1. Effect of nitrogen rates (0, 50, 100, 150 and 200 kg ha-1) on maize yield in the derived and southern guinea savanna zones of Nigeria.
The highest yield was obtained from 8516-12 and was followed by 8321-18. On the average, (8516-12) produced 17.5-33.5% grain yield more than other maize varieties in the southern guinea savanna. It also yielded more than other varieties by 23.6-57.6% in the derived savanna. The nitrogen use efficiency (NUE) of both maize types is indicated in Table 2. Mostly, the NUE values decreased with increase in nitrogen rates. The HBM utilized nitrogen more efficiently than the OP. On the average, every kilogram of N applied to 8516-12 produced 25.9 kg grain, while TZSR-W gave 19.7 kg grain, which showed the highest NUE among the different maize types, respectively. The NUE, however, was considerably higher in the southern guinea savanna than in the derived savanna. The OP and HBM grown in the southern guinea savanna gave 49-93% and 13-51% NUE, respectively higher than in the later.
Table 2. Nitrogen use efficiency of maize (kg grain kg N-1) as influenced by different rates of N application.
On the whole, at 50 and 100kg N ha-1 maize efficiently utilized nitrogen resulting into yields close to those obtained at higher rates. Optimum N application rate appeared to be 100 kg ha-1 in the derived savanna. The HBM however, responded well to higher levels such as 150 and at times 200kg N ha-1 in the southern guinea savanna. The best performance was shown by 8516-12 and was followed by 8321-18. Also, application of 100 kg Nha-1 appeared to be optimum for the OP in this zone. Regardless of type, maize responded positively well to P application. The control (0 kg P2O5 ha-1) gave the least yield that was significantly lower than other application rates (Figure 2). Application of 40 kg P2O5 ha-1 appeared to be optimum. Since, at higher rates, the yield was depressed. At Mokwa however, there was steady increase in grain yield of the HBM up to 60 kg P2O5 ha-1. The yield at this rate was significantly (p = 0.05) higher than applying 20 kg P205 ha-1, but not different from 40 kg P205 ha-1. Application of 80 kg depressed yield. The grain yield response of the OP to the different P rates was obtained only at 40 kg P205 ha-1. Higher rates resulted in yield decline.
Figure 2. Influence of phosphorus rates on maize yield in the
derived and southern guinea savanna zones of Nigeria.
The phosphorus use efficiency (PUE) of both open pollinated and hybrid maize is shown in Table 3. The higher the rate of P application, the lower the PUE. This indicates that the efficiency of maize in P utilization decreased as the P fertilizer rate was increased. On the average, every kilogram of P applied to maize at Ilora produced 8.4 kg and at Mokwa 10-13 kg of grain. The highest PUE was observed at 40 kg and 20 kg P2O5 ha-1 at Ilora and Mokwa, respectively. Additional use of 20 kg P205 ha-1 reduced the grain weight produced from every kilogram P by 35-40% at Ilora and 11-18% at Mokwa.
Table 3. Phosphorus use efficiency (kg grain kg P-1)
as influenced by different rates of P application.
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