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SummarySoil is a hetereogenous, dynamic, living system that supports life on earth. Soil health and soil quality are of great relevance in the present day agriculture due to the continuous degradation of soil. Soil acidity is an important parameter that affects the crop yield and quality. Among the acid soils, acid sulfate soils are of great importance because they occupy a considerable area and are potentially productive soils. The objective of this paper is to present a review about the constraints of acid sulfate soils like acidity parameters and nutrient dynamics that hampers crop production.

The most important factor limiting the soil application of sewage sludge is the presence of heavy metals. This study was conducted to evaluate the effect of composting on nutrient content, heavy metal (Cd, Cr, Ni and Pb) concentration and heavy metal fractions in the sewage composts with different bulking agents (sawdust and coirpith), heavy metal adsorbent (zeolite) and liming materials (lime and flyash). Experimental results revealed that sewage sludge composts were rich in organic carbon and plant nutrients. Total nutrients and heavy metal concentration showed an increasing trend towards the maturity of composts. Heavy metal fractionation studies pointed out that mobile fractions of heavy metals such as exchangeable and carbonate fractions decreased at the end of composting whereas the residual fractions increased which indicates that composting of sewage sludge with heavy metal adsorbent and different bulking agents decreased the mobility and bioavailability of heavy metals. The compost C8 (Sewage sludge + sawdust + zeolite (50:30:20) + flyash) was superior with respect to stabilization of heavy metals studied. The concentration of Cd, Cr and Pb were within the permissible limit as per Fertilizer Control Order (FCO). The addition of coal flyash and zeolite enhanced the stabilization of heavy metals due to the higher alkalinity and ion exchange capacity of flyash and zeolite respectively. Polyphenolic group and organic compounds present in sawdust also have the ability to bind heavy metal. The study revealed that composting is an effective technology for reducing the heavy metal bioavailability and the heavy metal speciation studies of the matured composts revealed that considerable portion of the heavy metals were associated with immobile fractions indicating less bioavailability and ecotoxicity.

A study was conducted to assess the soil carbon storage as different soil carbon pools in acid sulphate soils of Kuttanad, Kerala under different land uses and mapping of carbon stock using GIS. Surface soil samples (0-15 cm) were collected from three agricultural land use systems namely rice, coconut and rice-fish from six acid sulphate soil series viz. Ambalapuzha, Purakkad, Thakazhi, Thuravur, Thottapalli and Kallara and were analysed for soil carbon pools like  organic carbon, labile carbon, water soluble carbon, particulate organic carbon, microbial biomass carbon and mineralizable carbon using standard procedures .The carbon stock in soil was also computed  and mapped using Arc GIS  software.  The highest organic carbon content of 9.38% was recorded in Kallara series under rice land use. The water soluble carbon ranged from 44.38 to 208.68 mg kg-1. Labile carbon in soil varied form 4.36 mg g-1 to 13.06 mg g-1. Particulate organic carbon was the highest in rice land use in Kallara series (7.23%). The mineralizable carbon ranged from 2.17 mg kg-1 to 2.91 mg g-1. The microbial biomass carbon varied between 71 mg kg-1 and 488 mg kg-1. The humic acid content varied from 0.20% to 6.09% and the fulvic acid content ranged from 0.09% to 20.10%. The active and passive carbon pools and their contribution to total soil carbon pool was the highest in Kallara series. Among the different land uses, coconut had the highest active pool, while rice land use recorded the highest passive pool of carbon. The soil organic carbon stock (115.96 Mg ha-1)   and carbon pool index (2.10) were the highest in Kallara series. The proportion of POC to SOC was the highest in Kallara series (0.62) under rice land use indicating it as a potential carbon sink. The carbon turnover rate was found to be the highest in Thottapalli series (1.15) under coconut land use indicating it as a potential carbon source.

Background: Seed pelleting involves the sticking of target materials on to the surface of seeds. Pelleted seeds make planting of small seeds much easier by altering their shape, size and density. The call out on organic farming explains the requisite of user friendly and ecofriendly technique for seed management practices. The current study aimed to assess the effect of organic manure seed pelleting for enhancing soil properties, nutrient uptake and yield of rice.Methods: A pot culture experiment was carried out at College of Agriculture, Vellayani during the year 2018-19 to prepare organic manure seed pellets for rice and to evaluate its influence on yield, nutrient uptake and soil nutrient status. Pelleting materials were prepared using various treatment combinations namely, FYM + Azospirillum + Phosphobacteria (T2), vermicompost + Azospirillum + Phosphobacteria (T3), bioslurry flakes + Azospirillum + Phosphobacteria (T4), charcoal powder + Azospirillum + Phosphobacteria (T5), fly ash + Azospirillum + Phosphobacteria (T6), pongamia leaf powder + Azospirillum + Phosphobacteria (T7) and bioslurry + plant extracts + Azospirillum + Pseudomonas (T8: Farmer practice).Result: The results revealed that the highest grain yield (54.84 g pot-1) and straw yield (66.10 g pot-1) were recorded by T3. With regard to the uptake of nutrients, T3 registered the highest uptake of N, K, Ca, S, Zn, Cu and Si in grain and shoot. P uptake in grain was highest in the treatment T4 while T3 had the maximum P uptake in shoot. Nutrient status of the post-harvest soil was significantly influenced by the treatments.