Soil Fertility Status in Coconut after Long-term Drip Fertigation in Indo-gangetic Plain of South Bihar Alluvial Zone(a)

Abstract

It was reported that water resources and ground water reduces day by day but its consumption in different sector increases rapidly. In India agriculture is largest water consumer (81%) sector (WRI, 2007) and use of water in an efficient way is demand of time. It has been scientifically recognized that adoption of drip fertigation method is an option for efficient use of water and nutrients through improvement in crop yield per unit volume of water and nutrients used (Bar-Yosef, 1999;Patel and Rajput, 2011). Drip fertigation allows continuous irrigation and fertilizer injection into the root zone. Soil physicochemical properties are important aspects of soil quality that can change with long-term drip irrigation due to physical and chemical stress evidence of soil structural decline, such as increased bulk density under drip irrigation has been reported (Clark, 2004). Moreover, drip irrigation whereby a certain portion of the soil is wetted also causes the spatial variability of soil physical and hydraulic properties. Therefore, evaluation of spatial variability of soil characteristics and the vertical distribution of nutrients in soil under drip fertigation system can act as a very useful tool for the determination of fluctuations in soil behavior, especially its nutrient supplying capacity. Keeping the above facts in mind, the present investigation was carried out to know the soil fertility status under long-term drip fertigation system in coconut under All India Coordinated Research Project on coconut variety Shakhi Gopal Tall with long term drip fertigation system in BAU, Sabour under following treatments viz. T1 = Control, T2 = 25% of the recommended dose of NPK fertilizers (RDF) through drip system, T3 = 50% of the RDF through the drip system, T4 = 75% of the RDF through the drip system, T5 = 100% of the RDF through the drip system, T6 = 100% of the RDF through soil application. The results indicated that bulk density, particle density and pore space of soils were found to have no significant difference among the treatments and across different soil depths. Bulk density, particle density and pore space varied from 1.41 to 1.47 Mg m -3 , 2.23 to 2.25 Mg m -3 , and 31.9 to 36.6%, respectively, among all soils. Void ratio varied from 0.51 to 0.59 over all the soils. Void ratio and air-filled porosity were not significantly different among the treatments but significant difference was observed across the soil depths. Maximum water holding capacity of soils under different treatments across varying soil depths was not significantly different from each other. Soil pH and EC of all the treatments was not significantly different but decreased significantly with increasing soil depths. All the treatments for CEC and organic carbon content of soils were not found to be significantly different and depthwise were significantly different. Organic carbon content varied significantly among all the treatments and also across the varying soil depths. Available nitrogen, phosphorus and potassium content were low, medium and l...