Pramod Jha

Predicting Total Organic Carbon Content of Soils from Walkley and Black Analysis

Globally, there is problem of computing soil carbon stock because the Walkley–Black method gives only an approximation of soil organic carbon content. Until now, no universal relationship between Walkley–Black carbon (WBC) and total soil organic carbon (TOC) has been developed that could be applicable in all kinds of soil. In the present study, relationships between WBC and TOC were established from samples collected from central and northern India. TOC was measured by dry combustion technique and WBC was determined by wet digestion methods. A relationship between WBC and TOC was developed by taking into account silt + clay content (SICL) of soil and mean annual rainfall (MAR) of the region (adj. R2 = 0.99, n = 100). The present study gives an easy approach to measure TOC by easily available data sets (WBC, SICL, and MAR). Using this relationship, computation of soil carbon stock that was done earlier with WBC values could be revisited and improved.

Conservation Agriculture: A New Paradigm for Improving Input Use Efficiency and Crop Productivity

Conservation agriculture (CA) refers to a set of agricultural practices encompassing minimum mechanical soil disturbance, diversified crop rotation and permanent soil cover with crop residues to mitigate soil erosion and improve soil fertility besides soil functions. The CA aims to conserve, improve and make more efficient use of resources through CA-based technologies. It has many tangible and intangible benefits in terms of reduced cost of production, saving of time, increased yield through timely planting, improved water productivity, adaptation to climate variability, reduced disease and pest incidence through stimulation of biological diversity, reduced environmental footprints and ultimately improvements in soil health. However, weeds are a major biotic interference in CA, posing big defy towards its success unless all the principles are completely followed. Development of post-emergence herbicide and growing herbicide-tolerant crops and also the retention of crop residues as a mulch help in managing weed problems and also improve soil moisture retention. Furthermore, this practice of agriculture improves soil organic carbon content which ultimately leads to an increase in input use efficiency.

Ravines: Prospective Zone for Carbon Sequestration

Ravines are the extreme form of land degradation owing to water erosion and along with gullies of various sizes occupy about 10.37 million ha area in the country which could be utilized for sequestering carbon through improving vegetation densities/plantations. In fact, ravines are the most fragile ecosystems that have very low soil carbon content due to their light texture and poor aggregate stability. Thus, there is an urgent need to manage and restore these lands with suitable cultural and management practices. In fact, utilization of medium and deep ravine lands for regular cultivation always remains challenging; however, these ravines can be alternatively utilized for energy plantation, augmentation of fuel and fodder demands for local populace and production of hardy underutilized fruits and oil seed-bearing tree/shrub species. Ravine lands, which are economically unsuitable for agriculture, can be successfully stabilized by planting fast-growing species like bamboo on the gully beds and buffel grass/dhaman grass (Cenchrus ciliaris) on the side slopes and the interspaces of gully bed for economic utilization of gullied land. It was also evident that Acacia nilotica, Bambusa species and Aegle marmelos are highly suitable for ravine area and provide a substantial role in carbon sequestration under ravine landforms of Chambal and Yamuna river. Similarly, Prosopis juliflora and Azadirachta indica have greater ability for sustaining site productivity due to their greater leaf litterfall and fine root production under Yamuna ravines. In this chapter, an attempt has been made to address some of the issue of ravines vis-a-vis potential zone for carbon sequestration.

SOIL MICROBIAL POPULATION AND ENZYME ACTIVITIES UNDER ORGANIC, BIODYNAMIC AND CONVENTIONAL AGRICULTURE IN SEMI-ARID TROPICAL CONDITIONS OF CENTRAL INDIA

Present field experiment was conducted at the Indian Institute of Soil Science, Bhopal, India in a clayey soil (Typic Haplusterts) under soybean (Glycine max, cv. JS 335) wheat (Triticum durum, cv. HI 8498) cropping system in a randomized block design with seven treatments in four replications to study the changes in soil fungal, bacterial and actinomycetes population; and resultant enzymatic activities in soil under organic, biodynamic and conventional agriculture management. The results of study revealed that, the soil microbial population (bacteria, fungi and actinomycetes), soil enzyme activities and soil microbial biomass carbon were found in the order of organic > conventional ≥ biodynamic agriculture. The organic agriculture registered 27-102% and 28-111% higher enzymatic activities than conventional and biodynamic agriculture, respectively. Similarly, soil microbial biomass carbon was found 30-45% and 33-42% higher under organic agriculture management as compared to conventional and biodynamic agriculture management, respectively. No significant effect of biodynamic agriculture management on soil microbial properties was observed. * Corresponding author

Impact of Distillery Effluent on Soil Carbon and Nitrogen Dynamics in a Vertisol of Central India

ABSTRACT Distilleries produce a huge quantity of effluents, popularly known as spent wash (SW), which when bio-methanated produce post-methanation effluents (PME). A field experiment on soybean–wheat system was conducted for five consecutive years in a Vertisol of central India to evaluate the effect of distillery effluent (DE) on soil carbon and nitrogen dynamics. Ten treatment combinations consisting of control, 100% NPK + Farmyard Manure (FYM), and graded level of SW and PME were applied. Total carbon content of soil increased significantly with applications of FYM and DE. SW was found superior in enhancing carbon content of soil in comparison to PME. Farmyard Manure contributed more carbon toward the recalcitrant pool, whereas DE contributed more carbon toward the active and slow pool. Nitrogen (N) availability was significantly improved with the application of DE. Balanced application of DE may act as amendment for increasing C and N stocks in Vertisol.

Nitrogen Processes in Agroecosystems of India

Terrestrial ecosystem is the predominant agroecosystem in India in which N is the most widely used input. Nitrogen has played a key role in food grain production, although its use efficiency (20–50%) is very low in India and the recovery of residual N to succeeding crops is also very limited (<7% of applied N). Anthropogenic reactive N (Nr) in the earth atmosphere, hydrosphere, and biosphere has wider consequences, which are magnified with time as the Nr enters biogeochemical cycles. About 67% of the applied N fertilizer is ultimately converted back to the non-atmospheric N2 after alteration of N cycle and the rest of 33% Nr contributes to different ecosystems. Hence, judicious use of N based on proper understanding of N cycle must balance energy use efficiency and environmental safety while optimizing N resources for sustainable crop production.

Characterization of Humic and Fulvic Acid under Long-Term Integrated Nutrient Management of Soybean-Wheat Cropping System in Vertisol

The nature, content, composition and behavior of organic matter in soil are fundamentally important for growth of crops under diverse climatic conditions. Humic substances, present in soil, act as highly reactive natural polymers. The quality of soil organic matter according to functional groups governs the rate of sequestration of organic carbon. In the present investigation, effect of five years application of different integrated nutrient management (INM) interventions was assessed to note the changes in the fulvic acid and humic acid composition using fourier transform infrared (FTIR) technique. Humic acid and fulvic acid from selected treatments viz., control, inorganic NPK fertilizer (25, 30, 20 in soybean and 70, 30, 30 in wheat) and organic manure (8 t FYM ha−1 in soybean and 16 t FYM ha−1 in wheat) were fractionated from soil, separated and prepared for FTIR spectroscopy by following standard procedure. The obtained fractions were analyzed using FTIR spectroscopy. In control plot N-H stretching of amines, amides, aliphatic C-H stretching, C=O stretching of carboxylic acids, amides, ketones salt of carboxylic acid, C2H4-in plane deformation (−CCH), aromatic C-H out of plane bend were found in humic acids, whereas aliphatic C-H stretching asymmetric COO-stretching, C-O stretching of polysaccharides, -C-C-stretching were observed in fulvic acid. Due to long-term humification in treated plots humic acid contained more number of functional groups than fulvic acid. Results indicated that application of 8 t FYM ha−1 in soybean and 16 t FYM ha−1 in wheat in soil helped in the formation of long chain humic acid which can sequester more organic carbon and subsequently improve soil quality and health. Experimental results were discussed with respect to the utility of FTIR spectroscopy in the assessment of organic matter quality in long term fertilizer experiment.

Ameliorating Effects of Leucaena Biochar on Soil Acidity and Exchangeable Ions

ABSTRACT The amendment effect of Leucaena biochar was investigated in incubation study in acidic soil (pH (water (H2O)) = 4.5) of northwest India. The biochar (BC) was mixed at 2%, 4%, and 6% with soil and change in soil pH, electrical conductivity (EC), ammonium () and nitrate nitrogen (), exchangeable bases (calcium + magnesium, potassium, sodium) (Ca + Mg, K, Na), aluminum (Al), and Bray’s phosphorus (P) were measured periodically. The mean increase in soil pH was 0.65, 1.35, and 2.0 unit at 2%, 4%, and 6% (w/w) of biochar incorporation, respectively. Application of biochar significantly (P < 0.01) reduced ammonium () content of soil, whereas NO3-N concentration increased by threefold and fivefold by application of 2% and 4% (w/w) of biochar, respectively. Exchangeable soil potassium (K) and Ca + Mg concentrations increased with the application of biochar. Application of biochar above 2% (w/w) reduced exchangeable Al concentration to nondetectable limit. The study suggests Leucaena biochar may serve as an amendment for N transformation in highly acidic soil.