To elucidate the advantages of organic farming over inorganic farming in sustainable agriculture, experiments were conducted at Kerala Agricultural University, College of Agriculture, Vellayani using Cowpea (Vigna unguiculata subsp. sesquipedalis (L.) Verdcort) as a test crop. The experiments were carried out in a loamy skeletal kaolinitic rhodic haplustult soil. Different treatments tested were T1:Full recommended dose as per Package of practices recommendation (20 kg N ha-1, 30 kg P2O5ha-1 & 10 kg K2O ha-1 with 20 t FYM ha-1), T2: Full recommended dose as Farm Yard Manure, T3:Full recommended dose as FYM + P Solubilizing Micro-organisms, T4: Full recommended dose as Vermi compost, T5: Full recommended dose as Vermi compost + P Solubilizing Micro organisms, T6:Full recommended dose as Poultry manure, T7: Full recommended dose as Poultry manure + P Solubilizing Micro organisms, T8: Inorganic alone (20kg N ha-1, 30 kg P2O5ha-1 & 10 kg K2O ha-1). Farmyard manure, vermicompost and poultry manure were applied on the N content basis and additional requirements of P and K were met through application of rock phosphate and ash according to treatments. Phosphorus Solubilizing Microorganisms consisted of a mixture of Pseudomonas, Aspergillus and Azospirillum. Phosphorus Solubilizing Micro organisms @1 g plant -1 was applied in T3, T5 and T7 treatments. Entire P and K were applied basally and half the recommended N as basal and rest after two weeks of planting for all the treatments. The experiments were laid out in randomized block design with eight treatments and three replications. Lime was uniformly applied to all plots @ 250kg ha-1 to reduce the soil acidity. The results showed that organic farming practices improved physical, chemical and biological properties of the soil and helped for carbon sequestration. Organic manures also enhanced the soil enzyme activities such as dehydrogenase and phosphatase. All growth characters like height of plant, number and weight of nodules and leaf area index were found to be significantly boosted by organic treatments. The highest pod yield has been observed in Package of Practices recommendation treatment (T1) followed by vermi compost + P Solubilizing Micro organism’s application (T5). But these two treatments were on par statistically. Vermi compost + P Solubilizing Micro-organisms application showed pronounced effect on bhusa (total shoot weight) yield and total dry matter production. Pod nutrient composition as obtained from chemical analysis projected the role of organic manures in enhancing the pod nutrient content- N, P, K, Ca, Mg, Mn, Zn and Cu. Sulphur content was highest in poultry manure treatment. The influence of organic manure addition over inorganic nutrition was clearly highlighted in pod quality. Vermi compost application registered lowest value for crude fibre in cowpea. Regarding protein content, shelf life and organoleptic evaluation, organic treatments showed superior values over inorganic alone. The study revealed the favourable effect of organic nutrition in enhancing soil fertility and the quality aspects of cowpea pod in comparison with inorganic and integrated nutrition.

Wet land soils have got much importance in agriculture because they offer sustenance for rice, the staple food grain for majority of world population. Soil acidity is among the important environmental factors which can influence plant growth and can seriously limit crop production. Kerala, the southern most State of Indian peninsula with a geographical area of 38,864 km2 experiences a humid tropical climate with a mean annual rainfall of 3000 mm. 98% of the soils are acidic in nature and so the production potential of rice is highly reduced. In wet lands the cheapest method to alleviate acidity is by water management. Hence, the present study is been conducted in the rain fed low land rice soils of Kerala to unveil the effect of submergence on the kinetics of pH and available nutrients. Soil samples were collected from the 12 major rice growing tracts (3 each from each wet land tract) and invitro study was conducted by maintaining 5 cm water above soil for 12 weeks using CRD split plot design. The initial as well as fortnightly pH, available N, P, K, Na ,Fe,Mn,Zn,Cu ,Si and Al were determined by standard procedures.

All the soils studied were acidic except the black soils of Chittoor which are neutral to alkaline in reaction. Based on the severity of acidity, the wet land rice soils of Kerala can be arranged as Kari > Pokkali> Karapadom > Vellayani > Kayal > Kole > Wyanad > Pattambi > Kaipaid > Karamana > Kattampally > Chittoor. The wet lands under study showed an increase in pH due to submergence to a fairly stable value. All the wetlands reached above pH 5.5 within two weeks of submergence except Pokkali, Kari, Kayal and Kole lands. Since most soils contained more Fe (iii) oxide hydrates than any other oxidant, the increase in pH is largely due to the reduction of Fe. Kari and Pokkali soils are identified as Potential acid sulphate soils. For acid sulphate soils, keeping the soil under submergence, liming @ 1000 kgha-1 and washing away of acidity is been recommended. For all other soils two weeks of submergence prior to transplanting rice seedlings can create the optimum pH for rice without addition of lime. All the soils showed an increase in available N, P, K, Na , Fe , Mn and Si due to flooding. The peak increase was noticed during the first two weeks and then a slow build up was noticed. Available aluminium decreased to very low values in all soils except kayal, kari and Pokkali soils due to flooding. Al 3+ activity is directly related to pH, as pH rises due to flooding, aluminium is precipitated as hydroxides or sulphates.

Flooding a soil sets in motion chemical and electro chemical process that affect the supply of nutrients and their uptake by rice. After 2 to 4 weeks period of rapid changes, the processes tend to stabilize. The stable milieu favors rice because the nutrient supply is adequate and the level of toxins is low. A yield increase of about one tone ha -1 is been obtained by merely delaying transplanting for 2 weeks after flooding. After addition of green manures and organic manures during land preparation, two weeks submergence is a must in the rice fields of Kerala to increase pH, availability of nutrients and to minimize toxic elements like Al.

Productivity of coarse textured sandy soil is relatively low due to its extreme permeability which permits deep percolation of water and nutrients. Onattukara sandy tract is a fluvial and marine sand area of Alappuzha and Kollam districts of Kerala state in India which covers about 72550 ha. The cropping system practiced here is Rice-Rice-Sesame. Because of their low water holding capacity and high susceptibility to leaching of mobile nutrients, crops grown in these soils are more prone to water and nutrient stresses leading to low crop yields. For such soils reduction of seepage losses by reducing the relative proportion of macro pores through compaction has an important beneficial effect on growth and yield of rice (Oryza sativa) and Sesame (Sesamum indicum). Along with compaction, application of farm yard manure, coir pith and kayal silt will definitely improve soil physical properties such as water holding capacity, nutrient retention and soil structure. In order to alleviate the physical constraints of sandy soil and to enhance the nutrient and water use efficiencies, soil compaction along with the addition of farm yard manure, coir pith (waste material from coconut husk)and kayal silt( lake sediments) were tried to develop a new technology.

The field experiment is been conducted in a rice-rice-Sesame cropping system for three consecutive years at the Rice Research Station, Kayamkulam, and Kerala. The soil in this tract is sandy kaolinitic isohyperthermic psammaquent, highly permeable leading to high loss of nutrients and water. Design of the experiment was Factorial Randomized Block Design. The treatments consisted of the following factors-C0-No compaction;C1-Compaction with 400kg roller passing 4 times;F0-No farm yard manure;F1-2.5 t FYM;F2-5t FYM ha-1;S0-No kayal silt;S1-5 t ha-1Kayal silt;P0-No coir pith;P1-5 t ha-1coir pith(sieved).There are 18 treatments consisting of combinations of all the above factors excluding the combinations of S1 and P1 with other factors. After harvest of each crop soil physical properties, chemical properties, yield of crop and uptake of nutrients were analyzed using standard procedures. The first crop (rice), second crop (rice) and third crop (Sesame) recorded higher yield in compacted treatments when compared to non-compacted treatments. Compacting the soil of Onattukara sandy tract using 400kg roller passing 4 times at Procter moisture level with farmyard manure, coir pith and kayal silt has resulted in improvement of physical fertility of the soil. In the first crop rice the highest yield (3.15tha-1) was recorded by C1F1S0P1 (compaction+2.5t FYM+5t coir pith) treatment where as the same treatment without compaction gave only 1.60 t ha-1only half of the former.C0F0S0P0 treatment recorded a hydraulic conductivity of 6.86 cm/hr where as the same treatment with compaction reduced hydraulic conductivity to about half (3.24 cm/hr).The total uptake of N, P and K was increased significantly in compacted plots. The treatment C1F1S0P1 recorded lowest hydraulic conductivity in surface and sub surface layers and highest nutrient uptake. The yield increase in this treatment was due to reduction in leaching loss of nutrients by lowering the hydraulic conductivity and thereby increased uptake of nutrients. In second crop rice, the highest grain yield and straw yield was noticed in the C1F2S0P1 treatment. Highest root volume, leaf area index and N, P, K uptake were recorded by this treatment. Lowest hydraulic conductivity was also registered by this treatment. All these factors contributed for obtaining maximum yield in this treatment. Soil physical properties like bulk density, soil strength, mean weight diameter, micro porosity, water holding capacity and field moisture content were increased in compacted plots. Addition of FYM and coir pith enhanced the structural and moisture retention properties of soil. Compaction of coarse textured soils using 400 kg roller passing 4 times along with 5t ha-1 FYM and 5t ha-1 coir pith improved the soil physical properties, nutrient uptake and in turn yield of crops under rice based cropping system.