PERFORMANCE EVALUATION OF FERTIGATION EQUIPMENT ON CHILLIES AND MAIZE CROPS IN SANDY SOIL
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Date
2016
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Acharya N.G. Ranga Agricultural University, Guntur
Abstract
Soluble chemical fertilizers can be injected into the drip and sprinkler systems which can be easily applied to the crop. This way nutrients are delivered with the irrigation water, directly to the active root zone of the plants. The two operations namely, irrigation and fertilizer applications are done simultaneously which results savings of both in water and fertilizers along with labour requirement.
Precise management of irrigation quantity along with the rate and timing of nutrient application are of critical importance to obtain desired results in terms of productivity and Nutrient Use Efficiency. Therefore, for injection of the fertilizer solution into the irrigation system three different fertigation equipments were used namely, venturi injector, fertilizer injection pump and fertilizer tank for the present study.
The fertilizer injection pumps needs no external power supply, since the linear hydraulic motor contained within the unit, is powered by the hydraulic pressure of the irrigation system and directly connected to main line. A venturi injector with the size of ¾th inch manufactured by Netafim irrigation systems was used to evaluate the hydraulic performance. The pressure drop through a venturi must be sufficient to create a negative pressure (vacuum) as measured relative to atmospheric pressure. Under these conditions the fluid from the tank will flow into the injector. In fertilizer tank the water will flow because of pressure gradient between the entrance and exit of the fertilizer tank created by a pressure reducing valve (Throttle valve).
The experimental field with an area of 453 m2 for chillies crop and 440 m2 for maize crop was selected at field irrigation laboratory, Department of Soil and Water Engineering, College of Agricultural Engineering, Bapatla. The field was divided into 4 main plots with 4.8 m × 20.4 m with plant spacing of 0.6 m x 0.6 m size for chillies and
ii
4.6 m × 20.6 m size for maize crop with plant spacing of 0.6 m x 0.2 m to conduct experiments.
Different fertigation equipments like venturi injector, fertilizer injection pump and fertilizer tank were tested to study the hydraulic performance of the system. Venturi injector for fertilizer application was found to have high suction rate in comparison with fertilizer injection pump when pressure gradient increased between inlet and outlet. The percentage decrease in motive flow rate for venturi injector was 76 % which was higher than that of fertilizer injection pump 12 % and fertilizer tank 51 % for the pressure difference from 0.1 to 0.5 kg cm-2. Due to the high motive flow rate the venturi injector is suitable for application with large number of drippers where as fertilizer injection pump recorded less motive flow rate when compared to venturi injector at same pressure difference so we can use fertilizer injection pumps for smaller discharge rates also.
The results revealed that the yield response was observed to be the best in fertigation with fertilizer injection pump treatment in chillies crop as 10.51 t ha-1 with water use efficiency of 16.26 kg ha-1 mm-1 was observed to be higher than the all other treatments followed by venturi injector, fertilizer tank and flood method as 15.52, 12.66 and 9.18 kg ha-1 mm-1 respectively. In maize crop, also the yield was best in fertigation with fertilizer injection pump treatment as 6.10 t ha-1 with water use efficiency of 10.90 kg ha-1 mm-1 was observed to be higher than the all other treatments followed by venturi injector, fertilizer tank and flood method as 9.97, 8.47 and 5.75 kg ha-1 mm-1 respectively.
Increased FUE such as Nitrogen use efficiency (NUE) and Pottasium use efficiency (KUE) were observed in the chilli crop. The highest NUE of 35.53 kg of produce / kg of N was recorded in the treatment drip with fertilizer injection pump (T1) where as in maize crop the highest NUE of 30.96 kg of produce / kg of N was recorded in the treatment drip with fertilizer injection pump (T1). For chillies crop BCR was the highest for the treatment drip with fertilizer injection pump (T1) of 1.49 and the lowest for the control (T4) of 1.08. Venturi injector (T2) occupied the second position for BCR of 1.47 where as fertilizer tank (T3) recorded BCR as 1.20 whereas for maize crop BCR was the highest for the T1 of 1.48 and the lowest for the T4 of 1.15. Venturi injector occupied the second position for BCR of 1.41 whereas T3 recorded BCR as 1.20. It clearly indicates that at different methods of fertilizer application results had significant difference.
Key words: fertilizer injection pump, venturi injector, fertilizer tank, suction rate, motive flow rate.
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D5351
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