RESPONSE OF TOMATO (Lycopersicon esculentum Mill) TO FERTILIZERS IN RAYA VALLEY, NORTHERN ETHIOPIA

Abstract

Tomato is an important cash crop grown by smallholder farmers as well as private investors in Raya Valley, Northern Ethiopia. However, the yield of the crop has been low due to poor soil fertility status and use of improper rates of fertilizers. Three independent field experiments were conducted to investigate the response of tomato to fertilizers at Raya Valley for two consecutive seasons during 2016/17 using drip irrigation. The first field experiment was carried out to investigate the effect of nitrogen and phosphorus fertilizers on growth, yield, and fruit quality of a hybrid tomato variety known as “Gelilla". Factorial combination of five levels of nitrogen (0, 41, 82, 123, 164 kg N ha-1) and four levels of phosphorus (0, 20, 40, 60 kg P ha-1) were laid out in a randomized complete block design with three replications. Analysis of the results revealed that the highest marketable fruit yield (100.50 t ha-1) was obtained in response to the application of N164 and P40 kg ha-1. This treatment resulted also in the highest net revenue (393,130 Birr) with acceptable economic return and significantly increased marketable fruit yield of tomato by 228% compared to the control treatment. The second field experiment was conducted to investigate the effect of NP and vermicompost fertilizers on growth, yield, and fruit quality of a hybrid tomato. The treatments consisted of five levels of NP ((N0P0), (N41P0, (N0P20), (N41P20), (N82P40) kg ha-1) and three levels of vermicompost (0, 4, 8 t ha-1). The experiment was laid out in a randomized complete block design with a factorial arrangement and replicated three times. The highest marketable fruit yield (77.10 t ha-1) was recorded in response to the application of N82P40 kg ha-1and 8 t VC ha-1. This treatment resulted also in the highest net revenue (296,355 Birr) with acceptable economic return and significantly increased marketable fruit yield of tomato by 164% compared to the control treatment. The third field experiment was conducted to investigate the effect of blended and vermicompost fertilizers on growth, yield, and fruit quality of a hybrid tomato. Factorial combination of three levels of blended fertilizers (0, (200 NPSZn + 100 urea), (200 NPSFeZn + 100 urea) kg ha-1) and three levels of vermicompost (0, 4, 8 t ha-1) were laid out in a randomized complete block design with xviii three replications. The highest marketable fruit yield (79.54 t ha-1) was obtained in response to the application of 200 NPSZn + 100 urea kg ha-1and 8 t VC ha-1. This treatment resulted also in the highest net revenue (309,000 Birr) with acceptable economic return and significantly increased marketable fruit yield of tomato by 161% compared to the control treatment. Therefore, it is concluded that application of N164 and P40 kg ha-1 was found to be the best for optimal fruit yield of the crop. The other fertilizer rates, i.e. N82P40 kg ha-1and 8 t VC ha-1 as well as the application of 200 NPSZn + 100 urea kg ha-1and 8 t VC ha-1 resulted in 30% and 26% less fruit yield, respectively than the yield obtained from the optimum nitrogen and phosphorus treatments indicated above. This implies that nitrogen and phosphorus fertilizers are key for enhancing productivity of the crop in the region rather than applying blended and vermicompost fertilizers.