Effect of super-optimal levels of fertilizers on soil enzymatic activities during growth stages of wheat crop on an Inceptisol

A field experiment was conducted during 2010-2011 and 2011-2012 to investigate the effect of optimal (100% NPK) to super-optimal doses (200% NPK) of mineral fertilizers on soil enzymes such as dehydrogenase (DHA), acid phosphatase (Ac-PA), alkaline phosphatase (Alk-PA), fluorescien diacetate hydrolysis (FDA), urease and nitrate reductase (NRA) at three physiological stages (CRI, anthesis and maturity) of wheat crop on an Inceptisol. Dehydrogenase activity was reduced by 28-37% when fertilizer application was at super-optimal dose (200% NPK), whereas, urease and NRA responded positively in the range of 43-44% and 213-231% respectively. Alk-PAwas 7.3-7.9% higher in treatments receiving 125% NPK as compared to control (100% NPK); whereas, Ac-PA declines in the plots receiving 175 and 200% of recommended dose of fertilizer (RDF) as compared to 150% NPK levels. Addition of 175% RDF increased the FDA to the tune of 46-53% as compared to 100% NPK. A significant (P?0.05) positive interaction between fertilizer treatments and physiological stages of wheat growth was observed on soil enzyme activities (except urease and NRA) being highest at the anthesis stage of wheat. Correlation matrix analysis showed that DHA was correlated with the studied enzyme activities except Ac-PA and FDA; whereas, strong correlation was observed between urease and NRA (r=0.981, P=0.01). This study provides theoretical and practical base for avoiding super optimal application of fertilisers which hinders the enzyme activities and vis-a-vis sustainable nutrient enrichment under rhizosphere

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 we could not find a compiled source of information 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 literatures 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 in P (3.12%) and K (7.40%), while paper mill sludge biochar is highest 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 highest 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

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Not AvailableApplication of biochar to soil has increased considerably during recent years because of its effectiveness as a soil amendment causing beneficial effects on soil health. However, the effects have been reported to vary and depend upon types of feedstock and pyrolysis conditions during biochar production. Therefore, characterization of biochar is extremely important for its efficient utilization as a soil amendment. In the present study, biochar was prepared from agro-industrial by-products (rice husk and sugarcane bagasse) and weeds (Parthenium and Lantana) under similar pyrolysis conditions. Lantana biochar (LBC) showed the highest pH (10.4) while the lowest value (8.5) being recorded in rice husk biochar (RHBC). The energy-dispersive X-ray spectroscopy (EDS) analysis indicated that LBC and Parthenium biochar (PBC) were superior with respect to potassium (K) content than sugarcane bagasse biochar (SBBC) and RHBC. The Fourier-Transform Infrared Spectroscopy (FTIR) study exhibited the existence of different functional groups in biochar. All the biochar treated soils showed significantly higher microbial activities with different degrees. Application of LBC and PBC at 4.50 g kg−1 soil significantly increased K availability in soil. Lantana biochar and PBC amended the soil at 9 g kg−1 significantly increased the soil pH thus makes these biochar as potential liming materials.Not Availabl

Nitrogen and Sulphur Relations in Effecting Yield and Quality of Cereals and Oilseed Crops

Nitrogen and sulphur, both vital structural elements, are especially needed for the synthesis of proteins and oils. Investigations revealed the required application of sulphur is one half to one third the amount of nitrogen, and the ratio becomes narrower in mustard (Brassica juncea L.), followed by wheat and rice. The efficiency of an increased level of nitrogen required a proportionately higher amount of sulphur. A critical investigation on the effective utilization of applied vis-à-vis absorbed nitrogen in wheat and mustard envisaged accumulation of NO3-N in vegetative parts when sulphur remained proportionately low. Application of sulphur hastened the chemical reduction of absorbed NO3– for its effective utilization. The effect was more pronounced in mustard than in wheat. Easily available forms of sulphur, like ammonium sulphate and gypsum, as compared to pyrite or elemental sulphur, maintained adequate N to S ratio in rice, resulting in a reduction in the percent of unfilled grain, a major consideration in rice yield. A narrow N to S ratio, with both at higher levels, increased the oil content but raised the saponification value of the oil, a measure of free fatty acids. Whereas, a proportionately narrow N to S ratio at moderate dose resulted in adequately higher seed and oil yield with relatively low saponification value, associated with increased iodine value of the oil, indicating respectively low free fatty acids and higher proportion of unsaturated fatty acids, an index for better quality of the oil

Arsenic phytoextraction by Pteris vittata improves microbial properties in contaminated soil under various phosphate fertilizations

A greenhouse study was conducted to evaluate the phytoextraction of arsenic (As) by Chinese brake fern (Pteris vittata L.) from a highly contaminated Typic Haplustept soil treated with different phosphatic fertilizers (di-ammonium phosphate (DAP) and single superphosphate (SSP)). The fern was grown in two repeated growing cycles and the resultant changes in soil biological activities were examined in pot culture experiments. The biomass yield of the fern was recorded 8.17–12.33 g pot−1 in the first growing cycle and 5.73–10.90 g pot−1 in the second growing cycle. The fronds of P. vittata accumulated the highest quantity of As ranging from 2884 to 4504 mg kg−1 in the first growing cycle and from 2254 to 3803 mg kg−1 in the second growing cycle. The total As removal form the contaminated soil ranged from 19.4 to 44.5 mg pot−1 and 10.4 to 32.1 mg pot−1 in the first and second growing cycles, respectively. All the studied soil microbiological parameters were improved as a result of As phytoextraction in two successive growing cycles of the fern, for example, microbial biomass carbon, carbon mineralization, dehydrogenase activity, acid phosphatase activity, alkaline phosphatase activity and arylsulfatase activity were increased by 46, 38, 77, 37, 12 and 49%, respectively. The soil biological activities were improved as a result of decrease in the bioavailable pool of As by the action of phytoextraction. The phosphatic fertilizer management practices played a critical role in mobilizing As in the contaminated soil and thus enhanced the process of phytoextraction

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Not AvailableRockphosphate enriched pressmud compost (RPEPMC) was prepared by mixing fresh pressmud with rockphosphate (RP) inoculated with a composite microbial culture consisting of Pseudomonas spp., Aspergillus spp., Streptomycetes spp., Penicillium spp. and Trichoderma spp. at 0.1 % (w/w) level. The production of organic acids and solubilization of phosphorus during pressmud composting was studied at 30, 60, 90 and 120 days of composting. The presence of oxaloacetic, citric, succinic, tartaric, malic and maleic acids in the compost was detected and quantified. In general the organic acids produced at 30 days were highest which rapidly decreased at 120 days of composting. The positive influence of various organic acids on solubilization of P from RP was evident from concomitant increase in citrate-soluble and water soluble-P content in the compost. After 120 days of composting the end product had a stable C:N ratio and higher soluble P. Thus RPEPMC could be an alternative source of P fertilizer in crop production.Not Availabl

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Not AvailableInoculation of phosphate solubilizing bacteria (PSB) and phosphorus mobilizing arbuscular mycorrhiza (AM) with low quality rock phosphate (RP) can be an alternative source to one of the costliest phosphatic fertilizers in India, i.e. single superphosphate, by enhancing phosphorus influx and modification of root properties. Co-inoculation of PSB and AM may play a pivotal role to reduce phosphorus application through RP. Root properties and grain yield of irrigated soybean-wheat cropping system were evaluated with two levels of RP (100 and 50% recommended P (1.0 RP and 0.5 RP)) and different combinations ofPSB and AM with0.5 RP (0.5 RP + PSB, 0.5 RP + AM and 0.5 RP + PSB + AM) versus 100% recommended P application through soluble single superphosphate (1.0 SP) in the Indo-Gangetic plains. The P influx under 0.5 RP + PSB + AM and 1.0 SP were statistically at par with each other and the former treatment provided 0.6 and 3.2% higher value than the later in soybean and wheat, respectively. The root surface area density (RSAD) of soybean and wheat under 0.5 RP + PSB + AM (13.71 and 6.16m2 m−3, respectively) and 1.0 SP (13.70 and 6.37 m2 m−3, respectively) were non-significant and almost equal with each other. The values of root cation exchange capacity and other root properties under 0.5 RP + PSB + AM and 1.0 SP were also non-significant. The improved root properties under 0.5 RP + PSB + AM provided statistically at par grain yield with 1.0 SP for both soybean and wheat crops. The yield under 0.5 RP + PSB + AM of soybean crop was 3.4% higher than 1.0 SP. The net returns US$−1 invested was significantly higher under 0.5 RP + PSB + AM compared to 1.0 SP for both soybean and wheat crops. Coinoculation of PSB and AM with 50% of recommended P through RP could be recommended for better root properties and profitable grain yield of soybean-wheat cropping system in the Indo-Gangetic alluvial plains.Not Availabl

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Stabilization of Soil Organic Carbon as Influenced by Clay Mineralogy

© 2017 Elsevier Inc. There is a growing concern about climate change, and soils have attracted significant research attention as a sink for atmospheric CO 2 . Mechanisms of soil organic carbon (SOC) stabilization have received much focus recently due to its relevance in controlling the global C cycle. The purpose of this chapter is to review our existing knowledge of soil organic matter (SOM) dynamics with special reference to the role of clay mineralogy in the retention and stabilization of OC in soil. A good understanding of the stabilization mechanisms of SOM will help in adopting good management practices for SOM storage, improving soil structure and mitigation of greenhouse gas emissions. Here we present the SOM dynamics in relation to their sources and sinks, factors affecting SOC sequestration, and various processes involved in SOM stabilization. We critically review the studies examining soil, environmental, and management factors impacting SOM stabilization with a special reference to clay mineralogy. Finally, we present some future research needs in this area