Rate Determination of Nitrogen and Phosphorus Fertilizers for Green Maize Under Irrigation

Abebe Getu

doi:10.7176/jnsr/10-3-03

Abstract

A study was conducted on a research station at Kobo sub-center of Sirinka Agricultural research Center for two years to determine the optimum rates of N and P fertilizers for green maize production under irrigation in Kobo-Girana irrigation valley. Four levels of N (0, 46, 92 and 138 kg N ha -1 ) with three levels of P fertilizer (0, 23 and 46 kg P 2 O 5 ha -1 ) were factorially combined and laid in RCBD design with three replications. A uniform irrigation water depth and interval was applied to all plots based on maize’s irrigation water requirement determined for the area. The crop was irrigated a total amount of 500 mm irrigation water at 7 days interval starting from the development stage. Phosphorus fertilizer was applied all at planting. While, N fertilizer was applied in split, 1/3 at planting, 1/3 at knee height and 1/3 at tasseling stage. The result shows that there was no significant (p>0.05) interaction of N and P fertilizers on the cob yield, cob number, cob length and cob diameter of green maize. However, the main effect of N fertilizer had significant (p < 0.05) effect on the cob yield, cob number, cob length and cob diameter of green maize. The main effect of application of P fertilizer had insignificant (p>0.05) effect on the cob yield of green maize, which is attributable to the medium to high levels of Olsen’s extractable available P in bottom valleys of alluvial soils of Kobo where the study site laid. The highest cob number (51556) and cob weight (12.0 t ha -1 ) was recorded from application of 138 kg N ha -1 followed with statistically insignificant (p>0.05) difference by the cob number (49020) and cob weight (11.1 t ha -1 ) obtained from application of 92 kg N ha -1 . The partial budget and the sensitivity analysis result considering 15% possible price fluctuation show that the highest marginal rate return of 421.7% was obtained from application of 92 kg N ha -1 . While, the lowest marginal rate return of 378.8% was recorded from application 138 kg N ha -1 . Therefore, application of 92 kg N ha -1 is recommended for maximum and economic return of green maize production under irrigation in Kobo valley. Keywords: Green maize, kobo, irrigation, nitrogen, phosphorus. DOI: 10.7176/JNSR/10-3-03 Publication date: February 29 th 2020

Highlights

Low soil fertility is among the major factors limiting crop production and productivity in Ethiopia
The study was conducted for two years from 2013 - 2014 in Kobo irrigation study site of Sirinka Agricultural
The main effect of P fertilizer did not significantly affect the yield of green maize in both experimental years. This might be attributed to the existing medium to optimum levels of available phosphorus in the soil as elucidated in Table 1 which resulted in insignificant yield response to the application of P fertilizer

Summary

Introduction

Low soil fertility is among the major factors limiting crop production and productivity in Ethiopia. This is common in many tropical cropping systems where fertilizer use is low and little or no agricultural residues are returned to the soil for maintaining soil fertility. To increase crop productivity, the depleted soil plant nutrients should be replenished with chemical and organic fertilizers. Irrigation condition is different from rain fed condition in water distribution and crop water use efficiency (Tilahun et al, 2011 and Zhang et al, 1998). Plant nutrient uptake and use efficiency are variable in rain fed vs irrigation conditions since root density and soil moisture level are highly affected (Drechsel et al, 2015)

Methods

Results

Conclusion