PhD

Field experiments were conducted at College of Agriculture, Vellayani during April 2000 to January 2001 and April 2001 to January 2002 to assess the effect of organic manures and microbial inoculants on growth, yield and quality of ginger grown as intercrop in coconut garden, to evaluate its effect on the physical and chemical properties of the soil and to develop a suitable economic organic farming practice for producing export quality ginger free of pesticide residues.
Factorial combination of four organic manures (FYM, vermicompost, neemcake and green leaves) and four microbial inoculant treatment (no microbial inoculant, AMF, Trichoderma, AMF + Trichoderma) and two controls (package of practices recommendation of Kerala Agricultural university and absolute control) in RBD were studied. FYM @ 30 t ha-1 was applied uniformly to all plots except for absolute control. Organic manures were applied on nitrogen equivalent basis.
The main effects of organic manures, microbial inoculants and their interaction were studied. The application of FYM and AMF + Trichoderma increased plant height, number of tillers, number of leaves, root length, root spread, root weight, root volume, DMP, CGR, NAR, LAI, LAD, root shoot ratio, green ginger yield, dry ginger yield, shoot weight, bulking rate, rhizome spread, rhizome thickness, volatile oil, NVEE and uptake of N, P and K. The starch content as well as crude fibre content was less for FYM and AMF + Trichoderma treatment.
Soil physical characters viz., bulk density, particle density, water holding capacity and soil aggregate index were superior for FYM + green leaf treatment and AMF+ Trichoderma application. The available N, P and K content of the soil after the second year of experiment was higher for FYM + green leaves treatment and AMF + Trichoderma treatment. The organic carbon content of the soil was higher for FYM treatment. The soil pH was found to decrease after each experiment for organic manures, microbial inoculants as well as their combinations.
Among organic manure microbial interaction, application of FYM + AMF and FYM + neemcake + AMF + Trichoderma promoted significant growth and physiological characters, favoured green ginger yield, dry ginger yield, shoot weight, bulking rate, rhizome spread, rhizome thickness, quality parameters viz., volatile oil and NVEE. The application of FYM + AMF and FYM + neem cake + AMF + Trichoderma enhanced crop uptake of N, P and K and at the same time resulted in appreciable build up of available N, P and K in the soil.
The balance sheet for available N, P, K indicated a deficit balance during first year for all treatment except for absolute control. A gain in soil potassium content was noticed during the second year of experiment for all organic manures, microbial inoculants and organic manure microbial inoculant combinations.
The shoot borer attack was higher during the first year for FYM treatment at four month after planting and six month after planting compared to the second year. The nematode population in the soil was not significant before and after the experiment to cause economic damage. The residue analysis of plants treated with mancozeb, malathion and dimethoate as per package of practices recommendation of Kerala Agricultural University revealed no detectable level of residues.
The FYM + AMF and FYM + neemcake + AMF + Trichoderma generated a higher profit during the first and second year.
All organic manure microbial inoculant combination (except FYM + no microbial inoculant, FYM + vermicompost + no microbial inoculant, FYM + neemcake + no microbial inoculant, FYM + green leaf + no microbial inoculant) produced significantly higher yield and profit compared to treatments as per the package of practice recommendation of Kerala Agricultural University.
Correlation of yield with plant height, number of leaves, number of tillers, root length, root spread, root weight, root volume, dry matter production, crop growth rate, leaf area index, leaf area duration, shoot weight, bulking rate, rhizome spread, rhizome thickness, volatile oil, oleoresin and uptake of N, P and K showed significant positive correlation, which is an indication that these characters can be used as a criteria for the selection of yield.
To sum up FYM + AMF and FYM + neemcake + AMF + Trichoderma can be used as organic manure microbial inoculant combination with equal efficiency for ginger intercropped in coconut garden.
The result of two year study revealed that application of organic manure microbial inoculant combination produced better yield and improvement in soil health and nutrition than the application of organic manures or microbial inoculants alone. Increase in the profitability during the second year and reduction in the intensity of pest attack indicates the feasibility of switching over from integrated farming to organic farming.