Kunapajala is a fermented liquid organic manure mentioned in Vrikshayurvedha and now a days popular among farmers. A field experiment was conducted to evaluate the soil and foliar efficacy of 2% and 5% herbal and non- herbal Kunapajala on plant growth by using bhindi. Kunapajala treatment was compared with inorganic fertilizers, Panchagavya and fish amino acid. Foliar application of 5% non-herbal Kunapajala recorded the highest growth and yield attributes such as plant height (124.4 cm), number of branches (3.73), leaf area index (1.42) , dry matter production (3845.51 kg ha-1, number of fruits per plant (25.5), length of fruits (15.24 cm), girth of fruits (7.22 cm), average fruit weight (20.8 g) and yield (20.78 t ha-1).

Rapidly increasing levels of atmospheric CO2 and other greenhouse gases (GHGs) initiate unprecedented changes in climate systems, leading to severe ecological and economic disruptions. Climate change mitigation is possible through a reduction in net GHG emission by the process of carbon sequestration. Storage of carbon in a stable solid form through direct and indirect fixation in soil leading to carbon sequestration can result in an annual growth rate of 0.4% in the soil carbon stock and significantly reduce CO2 concentration in the atmosphere. The long term sequestration of carbon, viz, carbon stabilization is possible through both abiotic and biotic factors. This research paper aims to establish a literature review about the role of different agricultural management strategies for carbon sequestration and their stabilization mechanisms. Agricultural practices such as tillage, fallow elimination, erosion control and methane mitigation reduce carbon loss while crop management, nutrient management, land use systems, agro forestry and nano technology enhances carbon inputs. These agricultural management practices can facilitate carbon stabilization by acting through both biotic and abiotic mechanisms.

Biochar refers to the black carbon that is produced by the process of slow pyrolysis and act as a vehicle of carbon sequestration from renewable and sustainable biomass. This review describes the ability of biochar to improve the physical, chemical and biological properties of soil and thus increase crop yield and productivity. Benefits of application of biochar also includes lowering of bulk density, improving porosity, aggregation, water infiltration and water holding capacity of soils. It also darkens the soil colour which affects soil surface reflectance and thus helps to moderate soil temperature. Biochar addition enhances cation exchange capacity, increases soil pH, improves the supply and uptake of nutrients, reduces nutrient leaching losses, captures NH3 and leads to reduction in volatilization loss of nitrogen thus improving nutrient availability in soils. Application of biochar can also remediate soils contaminated with heavy metals and organic pollutants. It can also facilitate microbial colonisation in soil, enhance soil microbial biomass carbon, enzyme activity and the activity of mycorrhizal fungi.

Aim: To study the carbon fractional status of the growing media and to find out the best organic nitrogen source for fortification of thermochemical organic fertilizer, the manurial constituent of growing media for container cultivation of okra and tomato. Methodology: Container cultivation of okra and tomato were done in completely randomised design. Treatments included fortification with farmyard manure, neem cake, groundnut cake, poultry manure, vermicompost, coir pith compost, hatchery waste organic fertilizer, urea and unfortified thermochemical organic fertilizer. Carbon fractions, viz. total organic carbon, permanganate oxidisable labile carbon, microbial biomass carbon and soil respiration of the growing media were analysed. The yield and yield attributes of the crops were determined. Results: Irrespective of the organic source of nitrogen used, the fortified thermochemical organic fertilizer imparted a high status of total organic carbon to the growing media. Fortification with farmyard manure enhanced labile carbon, soil microbial biomass carbon and soil respiration over those fortified with other organic and inorganic sources. Container grown okra in a growing media with thermochemical organic fertilizer fortified with farmyard manure out yielded urea based fortification by 55.96%. Tomato grown in coir pith compost fortified growing media enhanced yield by 27.37% over the groundnut cake fortified growing media. Linear regression models of labile carbon with microbial biomass carbon (R2 = 0.8946) and with soil respiration (R2 = 0.9053) were significant and with a good fit. Interpretation: Fortification of thermochemical organic fertilizer with various organic sources of nitrogen imparted a high total soil organic carbon status. Synergic effect of the farmyard manure fortification was evident in labile carbon, microbial biomass carbon and soil respiration. Growing media fortified with farmyard manure was ideal for container cultivated okra whereas that with coir pith proved to be ideal for tomato, a solanaceous vegetable crop.

Biochar, an organic product of thermal decomposition of biomass in an oxygen limited environment can be used as a nutrient carrier to delay the release of nutrients into the soil, reduce nutrient leaching, and improve the nutrient utilization efficiency of fertilizers. Nutritional enhancement of biochar through fertilizer blending could be a low cost but high efficiency solution compared to non-blended fertilizers. However, the rate of nutrient release from the blended biochar fertilizer in different soils is ambiguous. Hence a 12 month incubation study was conducted in sandy soil (ultisol) of Thiruvananthapuram district of Kerala to elucidate the ammoniacal and nitrate nitrogen release rate and pattern from the produced paddy husk biochar, biochar and biochar bentonite (1:1) each blended with urea fertilizer in different ratios (1:0.5, 1:1, 1:2) including an absolute control. The individual effects of biochar, biochar-bentonite and urea were also studied. Paddy husk biochar was produced by the process of slow pyrolysis and biochar- blended urea fertilizers by the adsorbent process. To evaluate the influence of bentonite clay on the nutrient release pattern of biochar, it was blended with biochar and urea fertilizer. The highest total nitrogen content among the produced fertilizers was recorded in biochar: urea in 1:2 (33.04%) followed by biochar-bentonite: urea in a 1:2 ratio (31.13%). The incubation study revealed that the maximum release of ammoniacal nitrogen from soil+ urea fertilizer was at 30 days (115.73 mg kg-1) followed by a sharp decline, maintaining a low value till the end of incubation, whereas the release was sustained and gradually increased to reach a maximum at the 180th day (117.6 mg kg-1) for soil+ biochar: urea in 1:1 ratio. Nitrate nitrogen also followed the same trend with the maximum release observed for biochar: urea in 1:1 on the 150th day (151.2 mg kg-1). The release of nitrate nitrogen was more than that of ammoniacal nitrogen throughout the incubation period for all the treatments. Among the blended fertilizers, content of both ammoniacal and nitrate nitrogen were comparatively less for biochar –bentonite blended urea fertilizers. Thus, blending of urea with biochar/ biochar-bentonite prolonged the duration of maximum nutrient release.