ABSTRACT
184Land and water are the indispensable resources of life system. Water is the most limiting natural resource in arid and semiarid areas for the economic development of the country. In most of the areas, the only water available is the rain that falls on the area; hence, for successful agriculture, proper utilization of water is very essential which means to increase the water use efficiency of a crop by adopting water conservation measures. The water loss takes place in nature due to evaporation, transpiration, and percolation. The percolation losses can be avoided by applying water to the plant properly. The evaporation losses can be minimized by the use of mulches such as crop wastes, polyethylene plastics, and chemicals.
In many countries and regions, fresh water is relatively scarce, but there are considerable resources of saline water which could be utilized for irrigation if proper crops, soil, and water management practices are established. During the last three decades, micro irrigation systems owing to their capability to apply water efficiently, low labor and energy requirement, and increase in quantity and quality of crop yield/produce have made a breakthrough in many countries around the globe. Micro irrigation encompasses drip/trickle systems, surface and subsurface drip tapes, micro sprinklers, sprayers, microjets, spinners, rotors, and bubblers. It is a concept where water is applied at low rates frequently near the root zone of the plant and is successfully applied to the vegetable crops. In recent years, fertilizer is also applied along with water through drip irrigation to get higher fertilizer use efficiency besides increased yields.
The experiment was conducted in PFDC research and demonstration plot of TNAU, Coimbatore during December 2011 to April 2012 to study the effect of drip fertigation and mulching on tomato hybrid variety COTH-2. The experiments were laid out in factorial randomized block design with nine treatments which included three mulching levels such as 25 pm thickness plastic mulch, 50 pm thickness plastic mulch, and control and three fertigation levels including 80%, 100%, and 120% RDF which were replicated thrice.
The observations were recorded on biometric parameters, yield, soil temperature, wetted zone diameter, moisture distribution, and also soil physical and chemical properties. Based on the observations, the water use efficiency, fertilizer use efficiency, and benefit-cost ratio were worked out and statistical analysis was carried out for each observation to find out the significant effect on the treatment.
185Soil samples were collected before transplanting and after final harvest and were analyzed to find the physical and chemical properties of soil. The bulk density decreased from initial to final stage in the mulching treatments. In total, 50 gm thickness mulching treatments have observed greater reduction in bulk density, that is, from 1.4 to 1.34 g/cc. Particle density also showed similar results as that of bulk density. Porosity increased from initial to final. Maximum porosity is found in 25 gm thickness mulching treatment. The porosity of initial soil was 42%. After harvest, it changed to 45%.
After final harvest, it was observed that among most of the treatments, nutrient values were less in treatments with 80% recommended N, P, and K. It indicated that the fertigation applied in those treatments was fully taken up by the plants for their growth and yield. Also, we can see that the final nutrient has increased than the initial content in all the cases due to the application of the fertilizer. The available N in the initial soil was 131.2 ppm. After final harvest, it gets reduced in the 80% RDF treatments, and was less (118 ppm) in control plot. The maximum N (146 ppm) was found in 50 gm thickness mulch with 120% RDF, T6. The nutrients P and K also showed similar result as that of N.
The discharge from the drippers at different points of emission was measured for a particular period of time at 0.5 kgf/cm2 pressure and parameters such as coefficient of variation (Cv), the statistical uniformity (SU), and coefficient of uniformity (CU) were evaluated from the observed discharge. The Cv was obtained as 0.0198, SU as 98%, and CU as 96.87%.
Soil temperature was low in the early morning and gradually increased from 12 to 4 p.m. in all the treatments and then declined. Temperature under mulches was higher than that of the control plots for all the times. In mulching treatments, weeds were completely absent. Weeds were found only in the control plots and their numbers increased with respect to the increase in fertilizer application. Increased dry matter production of weeds was observed with advancement of crop growth.
The hybrid was assessed for the mean performance in respect of growth characters, namely, plant height, flowering traits, such as days to first flowering, first fruit set and first harvest, fruit characters, such as fruit weight, size, and yield.
The highest yield was recorded in T6 (85.96 t/ha), that is, in 50 gm thickness plastic mulching at 120% RDF followed by T5 and T3 (83.16 t/ha) and (81.22 t/ha), respectively, (Table 4.10, FIG. 4.13) and lowest yield was recorded in T7 (57.98 t/ha), that is, in control.
186The highest water use efficiency of 386 kg/ha mm was recorded in treatment T6 which is 50 gm plastic mulch with 120% RDF. The least water use efficiency (261 kg/ha mm) was noted in control (T7). Increased fertilizer use efficiency with the decreased level of fertilizer dose through drip was observed.
The fixed cost of installation of drip irrigation system and mulching sheets for 25 gm thickness treatments was Rs. 54,910 per ha and Rs. 51,710 for 50 gm thickness treatments per year. The treatment T6 registered the highest gross income of Rs. 416,100 per ha. The benefit-cost ratio was also higher (4.17) in this treatment (T6) compared to all other treatments. In control plot (T7) with 80% RDF, the benefit-cost ratio was (2.04), which is less than the other treatments.
Among all the mulching and fertigation treatments, the best performance in terms of growth, yield, and quality were observed in 50 gm thickness mulching treatment with 120% RDF. The results have indicated that the plastic mulching has higher benefit in terms of yield, quality, water use efficiency, and benefit-cost ratio as compared to other treatments.
