Soil Nutrient Dynamics Research Articles

Soil biodiversity and biogeochemical function in managed ecosystems

A complex combination of environmental, biological, chemical, and physical properties and processes determine soil biodiversity and its relationship to biogeochemical functions and ecosystem services. Vegetation, land-use, and land management, in turn, influence diversity and function in the soil ecosystem. The objective of this review was to assess how different land-use systems (crop production, animal production, and planted forest) affect soil biodiversity, and how consequent changes in soil biodiversity influence energy (carbon) and nutrient dynamics. Deficiencies in understanding relationships between soil biodiversity and biogeochemical function in managed ecosystems are highlighted, along with the need to investigate how diversity influences specific processes across different functional groups and trophic levels. The continued development and application of molecular techniques and data informatics with descriptive approaches will contribute to advancing our understanding of soil biodiversity and function in managed agricultural and forest ecosystems.

Differentiated response of plant and microbial C: N: P stoichiometries to phosphorus application in phosphorus-limited paddy soil

Phosphorus (P) application is an indispensable practice in agricultural crop production. However, the effect of P on crop and microbial biomass stoichiometries as well as its role in soil nutrient dynamics, remain poorly understood, thereby limiting our ability to predict the ecological consequences of agricultural practices. Herein, we conducted a P application experiment in a subtropical P-limited paddy soil to examine the effect of P addition on soil nutrient availability as well as on rice and the microbial C:N:P stoichiometries. The results showed that soil dissolved organic carbon (DOC) and available P content were simultaneously affected by P application and rice growth stage. Further, addition of P served to increase rice C and N content while decreasing the C: P and N: P stoichiometric ratios, indicating that P input contributed to rice growth and N absorption. Marked increases in soil microbial biomass carbon (MBC) and phosphorus (MBP) were also observed in soil treated with P. Moreover, the microbial C:N:P stoichiometry increased with rice growth stage, suggesting that changes in microbial and plant nutrient demand throughout the rice plant growth cycle causes competition between microorganisms and plants for N and P. Pearson's correlation and redundancy analyses revealed that available nutrients of soil were intercorrelated and regulated the patterns of rice and microbial C:N:P stoichiometries. In conclusions, P enrichment altered soil nutrient composition, microbial nutrient mining strategies, and rice C:N:P stoichiometry, thereby contributing to rice growth and improving crop yield.

Assessment of Soil Nutrient Status under Different Cropping Systems in Khotang, Nepal

Availability of plant nutrients in rhizosphere is directly influenced by types of crop grown and land use pattern. The experiment was conducted in Diktel Rupakot Majhuwagadhi Municipality, Khotang, Nepal to assess the soil nutrients dynamics as influenced by different cropping system. Five different cropping systems (Rice – Wheat, Maize – Millet, Maize – Vegetables, Ginger and Cardamom) were selected as treatments and all treatments were replicated for five times for blocking in Randomized Complete Block Design. Soil samples from 0-15 cm depth were collected from each site and evaluated for soil pH, soil organic carbon (SOC), total nitrogen (N), available phosphorus (P), and available potassium (K). All the tested parameters except N were found to be significantly affected by cropping system. Soil in all five cropping systems were found acidic (pH<6.5) in nature with pH ranging from 5.180-6.640. The SOC was recorded highest (3.102%) from Cardamom based system and lowest amount of SOC was observed in Ginger based system. The highest amount of P (32.14 mg/kg) was reported in Maize – Vegetables cropping system and lowest P content (5.72 mg/kg) was recorded from Cardamom based system. P content in Ginger based system (31.51 mg/kg) was statistically at par with that of Rice – Wheat system. The highest K content (306.50 mg/kg) was recorded from Maize – Vegetable cropping system and lowest K content (34.80 mg/kg) was observed in Cardamom based system which is statistically similar to Rice –Wheat (35.70 mg/kg) and Maize –Millet systems (77.20 mg/kg). The result indicated that cropping systems have huge impact on plant nutrient dynamics in soil.
 Int. J. Appl. Sci. Biotechnol. Vol 7(3): 341-346

Comparative Study on Khar Mulching and Forest Litter Mulching: Soil Nutrient Dynamics in Ginger Cultivation

A study conducted to assess the fertility status under Khar(Pragmites karka) and forest litter mulching practices on ginger cultivation. Ginger field with mulching of Khar and ginger field with mulching of forest litter was identified as two strata to collect soil sample. Thirty soil samples collected from each mulching practices. Simple random sampling procedure was followed to collect soil sample within the strata. Soil fertility parameters such as soil pH, Soil organic carbon, Nitrogen, Phosphorus, Potassium were analyzed for different mulching system. Mulching material significantly effect on Soil pH, Soil organic carbon and soil nitrogen. Soil acidity was found lower with forest litter mulch (5.53) but it was found higher for Khar mulch (5.78). Soil organic carbon was found higher in ginger field with Khar mulch (2.31%) and found lower with forest litter mulch (1.97%). Soil nitrogen level was found higher in ginger field with Khar mulch (0.20%) and found lower with forest litter mulch (0.17%). Soil available phosphorus and Potassium were not found significantly different in both type of mulching system. The result obtained from the study indicates that ginger field with Khar mulch result soil with higher soil organic carbon and Nitrogen. Mulching decision can also be made after testing the soil of respective ginger growing field. Appropriate liming could be done so that it could reduce the soil acidity problems.
 Int. J. Appl. Sci. Biotechnol. Vol 7(3): 335-340

The effect of tillage on nitrogen use efficiency in maize (Zea mays L.) in a ridge–furrow plastic film mulch system

The widely adopted maize planting pattern of ridge–furrow plastic film mulch (RFPM) in rainfed agricultural areas of the Loess Plateau has resulted in water-saving and increased yields. However, tillage practices used before RFPM may have had varying effects on the spatiotemporal dynamics of surface fertilizers and soil nutrients. To date, no studies have investigated the combined effects of tillage type and RFPM on crop performance. A two-year trial incorporated three treatments—conventional flat planting (CK), rotary tillage before RFPM (MR), and plow tillage before RFPM (MP). Within each treatment plot, a micro-plot was established to trace the fate of urea-N (only 15N labeled in 2017 and 2018). This study aimed to explore the effects of two tillage practices before RFPM on urea-N recovery by crops, crop growth, and water use efficiency.The RFPM significantly improved soil hydrothermal conditions during maize growth—the ridges had lower surface soil moisture contents than the furrows, with more moisture accumulation in the furrows—but water use efficiency did not differ between MR and MP. The spatial distribution of nutrients under RFPM differed between the two tillage practices. The ridges under RFPM had significantly higher soil organic matter (SOM) and total nitrogen (TN) than the furrows, more so in the MP furrows than the MR furrows. Soil NO3−-N did not significantly differ between ridges and furrows, but MP improved nitrogen use efficiency and significantly reduced N2O emissions, relative to MR. At harvest, MP had significantly higher yields than MR and CK, and the highest net income of the three treatments. In conclusion, plow tillage before RFPM had better economic and ecological benefits than rotary tillage and has the potential to help establish sustainable agricultural systems in dryland China.

Nutrients Dynamics in Peat Soil: Influence of Fluctuating Water Table

This study assesses the dynamics of nutrients in peat soil under fluctuating water table using designated soil columns. Results showed that the concentration of total N and mineral-N (NO3–N and NH4+-N) were maximized when the water table was maintained at 40 cm. When the water table was fluctuated between 0-40 cm depth (representing the water table during wet season), soil available P reached its highest concentration in the soil. The fluctuation of water table between 40 - 80 cm depth (representing the water table during dry season) allows the gradual release of exchangeable K, Ca, Mg and Na. The study indicated that the fluctuating water table affects the different nutrients differently.

Soil nitrogen and phosphorous dynamics by in situ soil experiments along an urban-rural gradient in Shanghai, China

An in situ soil experimental system was designed to determine how urbanization impacts soil nitrogen and phosphorus dynamics. Variables including the road density, normalized difference vegetation index, distance to the nearest highway and industrial area from the soil experimental site, land use impact index, population density, population change index, total population, and percentage of water area were used to quantitatively explain the soil nitrogen and phosphorous contents. The results showed that the total phosphorous in the soil increased slowly after September 2013, indicating a phosphorous accumulation phenomenon in the soil in urban areas. The nitrate nitrogen in the soil had a higher value in September 2013, while the soil ammonium nitrogen content was higher during the winter. Moreover, the soil ammonium nitrogen content was higher than the nitrate nitrogen content during most of the experimental period. The distance from the urban centre, road density, proportion of built-up land, and population density can explain the soil nutrient dynamics quantitatively, showing that 45.4% of the soil nitrate nitrogen content, 84.1% of the soil ammonium nitrogen content, 44.6% of the ratio of NO3/NH4, 58.1% of the ratio of total inorganic nitrogen (TIN)/total phosphorous (TP), and 81.6% of the TIN could be explained by one of these variables at most. The potential factors affecting the changes in soil N contents include changes in human dietary habits as more people migrate to cities and industrial wastewater discharge. This study is helpful in quantitatively understanding the urbanization process and associated environmental impacts.

Impact of warm‐season grass management on feedstock production on marginal farmland in Central Illinois

AbstractThe production of dedicated energy crops on marginally productive cropland is projected to play an important role in reaching the US Billion Ton goal. This study aimed to evaluate warm‐season grasses for biomass production potential under different harvest timings (summer [H1], after killing frost [H2], or alternating between two [H3]) and nitrogen (N) fertilizer rates (0, 56, and 112 kg N/ha) on a wet marginal land across multiple production years. Six feedstocks were evaluated including Miscanthus x giganteus, two switchgrass cultivars (Panicum virgatum L.), prairie cordgrass (Spartina pectinata Link), and two polycultures including a mixture of big bluestem (Andropogon gerardii Vitman), indiangrass (Sorghastrum nutans), and sideoats grama (Bouteloua curtipendula [Michx.] Torr.), and a mixture of big bluestem and prairie cordgrass. Across four production years, harvest timing and feedstock type played an important role in biomass production. Miscanthus x giganteus produced the greatest biomass (18.7 Mg/ha), followed by the switchgrass cultivar “Liberty” (14.7 Mg/ha). Harvest in H1 tended to increase yield irrespective of feedstock; the exception being M. x giganteus that had significantly lower biomass when harvested in H1 when compared to H2 and H3. The advantage H1 harvest had over H2 for all feedstocks declined over time, suggesting H2 or H3 would provide greater and more sustainable biomass production for the observed feedstocks. The N application rate played an important role mainly for M. x giganteus where 112 kg N/ha yielded more biomass than no N. Other feedstocks occasionally showed a slight, but statistically insignificant increase in biomass yield with increasing N rate. This study showed the potential of producing feedstocks for bioenergy on wet marginal land; however, more research on tissue and soil nutrient dynamics under different N rates and harvest regimes will be important in understanding stand longevity for feedstocks grown under these conditions.

Effects of Hardwood Biochar on Soil Acidity, Nutrient Dynamics, and Sweet Corn Productivity

ABSTRACTInterest is rising in amending agricultural soils with carbon-rich materials such as charcoal to improve soil fertility. The objectives of this field study were to evaluate sugar maple hardwood charcoal (biochar) as a soil amendment. The design of the experiment was split-plot with five replications, repeated over two growing seasons with sweet corn (Zea mays L.) production. Main plots were allocated to five application amounts of biochar including 0%, 2%, 4%, 6%, and 8% by weight (0, 40, 80, 120, and 160 Mg ha−1, respectively). Sub-plots consisted of applications of 0 or 56 kg nitrogen ha−1 as calcium ammonium nitrate. Soil pH increased from pH 5.8 to 6.7 with biochar additions. The percent base saturation was increased due to the retention of calcium, magnesium, and potassium. Soil phosphate availability increased. Sweet corn yield in the biochar-amended plots was depressed except with the 2% application. The result of the study revealed that no more than 2% application of sugar maple hardwood biochar should be applied for sweet corn growth.

Hierarchical drivers of soil microbial community structure variability in \u201cMonte Perdido\u201d Massif (Central Pyrenees)

Microbial activity is highly dependent on climatic factors (moisture and temperature) and edaphic characteristics in temperate ecosystems. Moreover, soil microbial community composition in high mountain areas is less known when compared to plant communities. In this study we investigated the soil microbial community from a functional perspective using PLFA (phospholipid fatty acid) methods in the four aspects of four summits (2,242 – 3,012 m above sea level) in the Spanish Central Pyrenees. Soil organic carbon (C), microbial biomass and nutrient dynamics (N{H}_{4}^{+} + N{O}_{3}^{-}, N mineralization and nitrification potential) were also determined. Microbial biomass C was highest in the lowermost summit and decreased by approximately 50, 14 and 12% with increasing altitude. In each summit soil N{H}_{4}^{+} and N{O}_{3}^{-} concentrations differed significantly among summits and aspects. Soil nitrification potential varied significantly between the factors summit and aspects, e.g., southerly vs. northerly, easterly vs. westerly aspects. Gram negative bacteria and Actinobacteria functional groups dominated the microbial community, with almost 40% of the total PLFA. Non-metric multidimensional scale (NMS) analysis showed that most of the PLFA functional groups were present in all summits and aspects, although with specific biomarkers. A high abundance of biomarkers 16:1ω9c and 16:0 2OH (gram negative bacteria) were obtained in the lowermost summit, while the biomarkers 16.1ω7cDMA (anaerobes) and 19:3ω6c (Eukaryote) were only found in the uppermost summit. Linear mixed model (lmm) analysis was used with summit as fixed effect and aspect as random effect. In general, our results demonstrate a fundamental role for environment, principally moisture, temperature and organic matter in explaining the pattern observed for soil PLFA biomarkers. Under a global change scenario, we need to shed light on the relationships between soil microbial functional groups and soil nutrient-related variables in order to identify the associated patterns of decomposition rates and soil processes driven by microbial communities in mountain areas. The results could thus be used in global predictive models on climate change impact on C or N cycles in these environments.

Generating a rule-based global gridded tillage dataset

Abstract. Tillage is a central element in agricultural soil management and has direct and indirect effects on processes in the biosphere. Effects of agricultural soil management can be assessed by soil, crop, and ecosystem models, but global assessments are hampered by lack of information on the type of tillage and their spatial distribution. This study describes the generation of a classification of tillage practices and presents the spatially explicit mapping of these crop-specific tillage systems for around the year 2005. Tillage practices differ by the kind of equipment used, soil surface and depth affected, timing, and their purpose within the cropping systems. We classified the broad variety of globally relevant tillage practices into six categories: no-tillage in the context of Conservation Agriculture, traditional annual, traditional rotational, rotational, reduced, and conventional annual tillage. The identified tillage systems were allocated to gridded crop-specific cropland areas with a resolution of 5 arcmin. Allocation rules were based on literature findings and combine area information on crop type, water management regime, field size, water erosion, income, and aridity. We scaled reported national Conservation Agriculture areas down to grid cells via a probability-based approach for 54 countries. We provide area estimates of the six tillage systems aggregated to global and country scale. We found that 8.67 Mkm2 of global cropland area was tilled intensively at least once a year, whereas the remaining 2.65 Mkm2 was tilled less intensely. Further, we identified 4.67 Mkm2 of cropland as an area where Conservation Agriculture could be expanded to under current conditions. The tillage classification enables the parameterization of different soil management practices in various kinds of model simulations. The crop-specific tillage dataset indicates the spatial distribution of soil management practices, which is a prerequisite to assess erosion, carbon sequestration potential, as well as water, and nutrient dynamics of cropland soils. The dynamic definition of the allocation rules and accounting for national statistics, such as the share of Conservation Agriculture per country, also allow for derivation of datasets for historical and future global soil management scenarios. The resulting tillage system dataset and source code are accessible via an open-data repository (DOIs: https://doi.org/10.5880/PIK.2019.009 and https://doi.org/10.5880/PIK.2019.010, Porwollik et al., 2019a, b).

The effect of biochar amendment to soils on Cnaphalocrocis medinalis Guenee (Lepidoptera: Pyralidae) on rice

Biochar application to soils can alter soil nutrient dynamics and thus change the uptake of nutrients by plants. The effect of such changes on leaf-chewing caterpillars remains unknown. In this study, we examined the effect of biochar amendment at varying rates on the developmental and reproductive performances of the rice leaf-folder Cnaphalocrocis medinalis on potted rice, and investigated C. medinalis population size over two years in a paddy field applied with biochar. We found that biochar amendment prolonged larval development, increased larval mortality, decreased mature larval body weight, lowered consumption of rice leaves, and reduced adult longevity of C. medinalis. We did not detect a difference in fecundity of the females that survived to adulthood among biochar treatment levels. The two-year paddy field experiment showed a reduced C. medinalis population as a consequence of biochar application in the first year, and a population similar to the control in the next year. The results from the current research suggest that biochar can impair C. medinalis development and may have a negative consequence on its populations.

Effect of localised phosphorus application on root growth and soil nutrient dynamics in situ – comparison of maize (Zea mays) and faba bean (Vicia faba) at the seedling stage

Root morphological response to localised phosphorus (P) application plays a crucial role in P acquisition. However, detailed knowledge of when and where roots respond to P patch (localised P supply) in situ is still lacking. X-ray Computed Tomography (CT) was used to quantify the root response to localised and uniform triple superphosphate supply in maize (Zea mays) and faba bean (Vicia faba). Soil solution was extracted by micro suction cups. On the spatial scale, X-ray CT results showed that maize roots proliferated in the P patch, resulting in higher root length density compared to the uniform P supply. On the temporal scale, the proliferation of maize roots into the patch occurred as early as 11 days after sowing. Faba bean showed no response to the P patch during the experimental period. In soil solution, localised P fertiliser supply not only increased the concentration of P and calcium, elements present in the fertiliser, but also potassium and magnesium. Our results indicate a fine-scale time pattern for P concentration in the local site to enhance root proliferation of maize but not faba bean, which suggests an evident difference in root response to local P supply between maize and faba bean at the seedling stage.

Effects of land use on soil organic and inorganic C and N at 137Cs traced erosional and depositional sites in mountain agroecosystems

Patterns of erosion, transport and deposition of soil particles not only affect the distribution of mineral fraction of the soil but their organic components. The spatial variability of soil nutrients in Mediterranean mountain agroecosystems that combine complex land uses and abrupt topography is poorly documented despite emerging concerns on nutrients fate require understanding the potential impact of soil erosion on nutrients redistribution across landscapes. This study aims to assess at catchment scale the spatial patterns of soil organic and inorganic carbon (SOC, SIC), soil organic carbon fractions and total nitrogen (TN) in relation to land uses and soil redistribution. To this purpose we selected a well characterized endorheic catchment located in NE Spain where soil erosion and deposition rates derived from 137Cs measurements were previously documented and we mapped the distribution of cropland and rangeland areas. A grid of 100 × 100 m was established for collecting a total of 205 soil samples for nutrients and standard soil analyses.In both rangeland and cropland the patterns of SOC and TN stocks were clearly related to 137Cs inventories thus significantly lower nutrient stocks (SOC: 34.1 ± 18.6 Mg ha−1, TN: 2.9 ± 1.7 Mg ha−1) were found in erosional sites whereas higher stocks (SOC: 44.9 ± 24.2 Mg ha−1, TN: 3.9 ± 2.3 Mg ha−1) were recorded in depositional areas. In cropland the mean nutrients contents (SOC: 1.1 ± 0.8%, TN: 0.1 ± 0.1%) were significantly lower than in rangeland (SOC: 3.2 ± 2.1%, TN: 0.2 ± 0.1%). The highest C/N ratios (29) were found in rangeland, while in cropland they occurred in depositional areas with their values below 10 in the erosional sites. In turn, the SIC content (range 0.4 to 10.2%) was slightly lower at the depositional sites (4.9 ± 2.2%) but not significantly different from the erosional sites (5.1 ± 2.2%). Cultivated and steep slopes led to loss of soil and nutrients due to intense erosion processes also related to tillage and crop productivity. Our findings provide evidence that the combined effect of land use and soil redistribution exert an important control on the spatial distribution of nutrients, highlighting a significant decrease of SOC and TN stocks with increasing soil erosion in croplands. The information gained achieves a better understanding of soil nutrients dynamics and further knowledge for effective land management of mountain agroecosystems in the Mediterranean region.

Consequences of Mississippi River diversions on nutrient dynamics of coastal wetland soils and estuarine sediments: A review

Coastal Louisiana is dominated by the Mississippi River Deltaic Plain, which is composed of a series of overlapping and truncated sub-delta lobes that formed an extensive coastal wetland – open water shallow bay and low relief upland mosaic across the entire coastal zone (∼25,000 km2). These coastal wetlands have been eroding at an alarming rate during the past century, coincident with major modifications to the deltaic landscape. One of these former modifications included extensive leveeing of the Mississippi River, essentially isolating the river from the coastal basins. One restoration technique involves re-connecting the previously isolated coastal basins to the river via diversions, which would once again allow the influx of freshwater, sediments and nutrients into the coastal basins. We review issues on potential impacts of nutrient loading from the river as a consequence of river diversions, focused on nitrogen (N) and phosphorus (P) dynamics including denitrification related to carbon dynamics. We also examined how water residence times in these shallow systems, compared to deeper, often seasonally stratified, coastal systems, are more likely to lead to greater N removal potential in the context of a large scale river diversion helping to reduce N transport to the coastal ocean.

Effect of tillage on macronutrients in soil and wheat of a long-term dryland wheat-pea rotation

Tillage is known to significantly affect crop residue decomposition and soil nutrient dynamics, but the impacts of tillage on soil and plant macronutrients concentration with time have not been reported. This study was conducted (i) to assess the influence of tillage timing and intensity on soil and wheat (Triticum aestivum L.) macronutrient concentration of a winter wheat-dry pea (Pisum sativum L.) rotation (WW-P) under a dryland cropping system, and (ii) to compare macronutrients in the tillage treatments with a nearby long-term grass pasture (GP). The tillage treatments were fall tillage (FT), spring tillage (ST), no-tillage (NT) and disk/chisel tillage (DT/CT). Soil samples from 1995, 2005, and 2015 were analyzed to determine the concentration of soil organic carbon (SOC), total N and S, Mehlich III extractable P, K, Ca, and Mg, and soil pH. The impact of tillage on soil macronutrient concentration was evident after 52 years of WW-P. As a result, greater concentration of SOC, total S, and extractable P, and K were observed under NT than under FT or ST. The WW-P plots lost 28, 46, and 67% of SOC, Mg, and S, respectively, in the top 10 cm of soil compared with the GP plots, whereas the NT plots were the only plots in WW-P to maintain a P concentration (99 mg P kg−1) comparable with GP plots (102 mg P kg−1) at the same depth. The results indicated that NT could be beneficial to recharge the soil nutrient pool over time compared to FT or ST.

Soil Nutrient Dynamics and Nitrogen Fixation Rate Changes over Plant Growth in Temperate Soil

Research on the use of soil enhancer materials such as biochar from soil chemical perspective still provide differing results; therefore, investigations focusing on soil-biochar-plant interactions are still necessary to constrain our understanding of complex biochar effects. The present study investigated the changes in biological nitrogen fixation rates (BNF) and overall nutrient dynamics (NO3−, NH4+, total N, K2O, and P2O5) during the growth of Capsicum annuum (pepper) in pot experiments amended with biochar made of paper fiber sludge and grain husk. Four treatments were studied with 0, 0.5%, 2.5%, and 5.0% (by weight) added biochar (BC) amount to temperate silt loam soil. Peppers were planted at 2–4 leave stages and grown for the duration of 12.5 weeks. Our results showed that total nitrogen had relatively small changes in all treatments over time compared to the dynamic changes observed in the case of inorganic nutrients. NO3−-N and NH4+-N abundances presented a continuous decrease during the course of the study after an initial increase. The pepper plant facilitated the BNF rates to triple in the control soils, while plants were in the growing phase (weeks 1–6), which further increased an additional 61% by harvesting (week 12). A high amount of biochar addition suppressed potential BNF rates of the investigated soil, indicating its potentially negative effects on soil indigenous microbial communities if added in excess. We also found a plateau in plant biomass production that after reaching an optimal (2.5%) biochar amendment in the soils, and excess biochar addition did not result in significant changes in the soils’ pH to achieve better nutrient (potassium, nitrogen, phosphorous) use or crop growth.

A review on biochar modulated soil condition improvements and nutrient dynamics concerning crop yields: Pathways to climate change mitigation and global food security

The beneficial role of biochar on improvement of soil quality, C sequestration, and enhancing crop yield is widely reported. As such there is not much consolidated information available linking biochar modulated soil condition improvement and soil nutrient availability on crop yields. The present review paper addresses the above issues by compilation of world literature on biochar and a new dimension is introduced in this review by performing a meta-analysis of published data by using multivariate statistical analysis. Hence this review is a new in its kind and is useful to the broad spectrum of readers. Generally, alkalinity in biochar increases with increase in pyrolysis temperature and majority of the biochar is alkaline in nature except a few which are acidic. The N content in many biochar was reported to be more than 4% as well as less than 0.5%. Poultry litter biochar is a rich source of P (3.12%) and K (7.40%), while paper mill sludge biochar is higher in Ca content (31.1%) and swine solids biochar in Zn (49810 mg kg−1), and Fe (74800 mg kg−1) contents. The effect of biochar on enhancing soil pH was higher in Alfisol, Ferrosol and Acrisol. Soil application of biochar could on an average increase (78%), decrease (16%), or show no effect on crop yields under different soil types. Biochar produced at a lower pyrolysis temperature could deliver greater soil nutrient availabilities than that prepared at higher temperature. Principal component analysis (PCA) of available data shows an inverse relationship between [pyrolysis temperature and soil pH], and [biochar application rate and soil cation exchange capacity]. The PCA also suggests that the original soil properties and application rate strongly control crop yield stimulations via biochar amendments. Finally, biochar application shows net soil C gains while also serving for increased plant biomass production that strongly recommends biochar as a useful soil amendment. Therefore, the application of biochar to soils emerges as a ‘win-win strategy’ for sustainable waste management, climate change mitigation and food security.

Long Term Fertilizer Management Effect on Nutrient Dynamics in Rainfed Rice-lentil System in Transect 4 of IndoGangetic Plain

The present study analyzed the effect of different organic and inorganic fertilizers on soil nutrient dynamics in a long-term field experiment under rainfed rice-lentil system. The experiment was operative at Agricultural Research Farm, Institute of Agricultural Sciences, B.H.U Varanasi, Uttar Pradesh, India. Carbon dynamics was investigated on surface soil on the basis of distribution of Walkley & Black Carbon, in active pool (AP) or labile carbon (oxidisable at low concentration of H2SO4) in relation to passive pool (PP) or non labile carbon (oxidisable at high concentration of H2SO4) and its indices carbon management index (CMI). The effect of eight different treatments including unfertilized, 100% N from farm yard manure, 100% recommended dose of fertilizer, 50% RDF + 50% N Foliar), 50% RDF, 50% RDF + 50% N FYM), 50% N FYM and Farmers practices i.e. application of 20kg N ha-1 The availability & uptake of major nutrients were studied. The results revealed: That mixed application of inorganic fertilizers and FYM substantially increase the soil organic carbon pool, sustainability index over remaining treatments. Higher fertilizer application rates resulted in higher and sustained crop yields which had been reflected in sustainability yield index. A significant Pearson correlation was found between SOC, AP, PP, exchangeable K2O content, soil microbial biomass carbon and SYI. (The result indicated to adopt conjunctive use of nutrient management which promote the SOC more labile and, induce availability of other nutrients coupled with SMBC that translate into higher crop yields.

Post-fire soil nutrient dynamics in a tropical dry deciduous forest of Western Ghats, India

BackgroundThe effect of forest fire on soil is complex and relatively less understood than its above ground effect. Understanding the effect of fire on forest soils can allow improving management of valuable forest ecosystems as adequate and proper information is very important for efficient management. We have studied the recovery of soil properties after fire, using a chronosequence approach (two, five and fifteen years after fire and control). Soil samples were collected from each plot of four fire patches (B0, B2, B5 & B15) from three different depths viz. 0–10 (Top), 10–20 (Middle), and 20–30 cm (Bottom).ResultsSoil organic carbon was lower than unburned plots after the fire and could not recover to the level of unburned plot (B0) even in 15 years. Total N, available P, and extractable K were lower 2-years and 5-years after the fire but are higher than unburned plot after 15-years. Available nitrogen (NO3− and NH4+) remain unchanged or higher than B0 in burned patches. Soil pH, Bulk Density, Water Holding Capacity, and Electrical Conductivity was lower initially after the fire. Forest fires have affected soil properties considerably. The response of soil properties varied with years after fire and soil depth.ConclusionForest fires occur very frequently in the study area. Significant quantities of carbon and total nitrogen are lost to the atmosphere by burning of litter, duff, and soil OM. Because nitrogen is one of the most important soil nutrients, the recapture of N lost by volatilization during a fire must receive special attention. Long-term studies are required to better understand the recovery of soil nitrogen.