Soil Sci. Soc. Am. J. 72:775–785 doi:10.2136/sssaj2006.0378 (original) (raw)
Related papers
Organic amendments influence soil organic carbon pools and rice–wheat productivity
Soil Science Society of America Journal, 2008
Soil organic C (SOC) pools under long-term management practices provide information on C sequestration pathways, soil quality maintenance, and crop productivity. Farmyard manure (FYM), paddy straw (PS), and green manure (GM) along with inorganic fertilizers were used in a 19-yr-old rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system in subtropical India to evaluate their impact on SOC stock, its different pools-total organic C (C tot ); oxidizable organic C (C oc ) and its four fractions of very labile (C frac1 ), labile (C frac2 ), less labile (C frac3 ), and nonlabile C (C frac4 ); microbial biomass C (C mic ); and mineralizable C (C min ). Cropping with only N-P-K fertilization just maintained SOC content, while N-P-K plus organics increased SOC by 24.3% over the control, their relative effi cacy being FYM > PS > GM. A minimum of 3.56 Mg C ha −1 yr −1 was required to be added as organic amendments to compensate for SOC loss from cropping. The passive (C frac3 + C frac4 ) pool and C min constituted about 39 and 11.5%, respectively, of C tot . Organics contributed toward the passive pool in the order FYM > PS > GM. Most of the pools were signifi cantly (P = 0.005) correlated with each other. Yield and sustainable yield index were strongly related with C frac1 , C oc , C mic , and C min . Results suggest C frac1 as a useful indicator for assessing soil health, and balanced fertilization with FYM as suitable management for sustaining crop productivity of the rice-wheat system.
Plant and soil, 2007
Soil organic carbon (SOC) pools are important in maintaining soil productivity and influencing the CO2 loading into the atmosphere. An attempt is made here to investigate into the dynamics of pools of SOC viz., total organic carbon (C tot), oxidisable organic carbon (C oc) and its four different fractions such as very labile (C frac 1), labile (C frac 2), less labile (C frac 3) and non-labile (C frac 4), microbial biomass carbon (C mic), mineralizable carbon (C min), and particulate organic carbon (C p) in relation to crop productivity using a 34 year old rice (Oryza sativa L)–wheat (Triticum aestivum L)–jute (Corchorus olitorius L) cropping system with different management strategies (no fertilization, only N, NP, NPK and NPK + FYM) in the hot humid, subtropics of India. A fallow treatment was also included to compare the impact of cultivation vis-à-vis no cultivation. Cultivation over the years caused a net decrease, while balanced fertilization with NPK maintained the SOC pools at par with the fallow. Only 22% of the C applied as FYM was stabilized into SOC, while the rest got lost. Of the analysed pools, C frac 1, C mic, C p and C min were influenced most by the treatments imposed. Most of the labile pools were significantly correlated with each other and with the yield and sustainable yield index (SYI) of the studied system. Of them, C frac1, C min, C mic and C p explained higher per cent variability in the SYI and yield of the crops. Results suggest that because of low cost and ease of estimation and also for upkeeping environmental conditions, C frac1 may be used as a good indicator for assessment of soil as to its crop productivity.
Communications in Soil Science and Plant Analysis, 2020
A profound consideration of soil organic carbon (SOC) and SOC pools as affected by the long-term use of fertilizer in a fixed crop sequence is essential to understand and maintain the health and productivity of soil. The dynamics of SOC pools, i.e. total soil organic carbon (TOC) and its different fractions under a rice-wheat cropping system subjected to various fertilizer management strategies over 42 years was investigated near Uttarakhand, India. The soil at the experimental site was an Aquic Hapludoll consisting of a poorly drained silty clay loam (1-1.5 m deep) overlying loamy to sandy sediments. Over 42 years, application of 100% NPK+ FYM (Farm Yard Manure) was the most effective management system in increasing organic C up to 0 to 60 cm soil depths under rice-wheat sequence. The combination of this integrated input application (100% NPK + 15 t ha −1 FYM) significantly built organic carbon fractions like total organic carbon, microbial biomass C (MBC), particulate organic C (POC), KMnO4 oxidizable C, Humic C, Fulvic C, Humin C, water-soluble carbon and hot water extractable carbohydrates at all four soil depths. Hence, application of FYM along with NPK resulted in a significant positive building up of all pools in the treatment at all four depths. Therefore, balance fertilization is panaceally important for sustaining improved soil health with balanced organic status and production potentiality of the soil for rice-wheat cropping sequence.
Biology and Fertility of Soils, 2008
Labile fractions of soil organic C (SOC) can respond rapidly to changes in C supply and are considered to be important indicators of soil quality. An attempt is made in this paper to investigate into the dynamics of total organic C (C tot ), oxidisable organic C (C oc ), very labile C (C frac 1 ), labile C (C frac 2 ), less labile C (C frac 3 ), non-labile C (C frac 4 ), microbial biomass C (C mic ), mineralizable C (C min ) and particulate organic C (C p ) in relation to the system productivity of a 20-year-old rice (Oryza sativa L)-berseem (Trifolium alexandrium L) cropping system with different management strategies [no fertilization, only NPK and NPK+ FYM (farmyard manure) applied in different seasons] in the hot humid, subtropics of India. Cultivation over the years caused a net decrease, while balanced fertilization with NPK maintained the SOC. About 62% of the C applied as FYM was stabilized into SOC. The passive pool (C frac 3 +C frac 4 ) constituted about 55% of the C tot . A larger proportion (63%) of applied C was stabilized in the passive pool of SOC. Of the analysed pools, C frac 1 , C mic , C p and C min were influenced most by the treatments imposed and explained higher per cent variability in the yield of the crops.
Field Crops Research, 2012
We studied the long-term effect of nutrient management on soil fertility and soil organic carbon (SOC) pools under a 6-year-old pearl millet-wheat cropping system in an Inceptisol of subtropical India. Significant build-up in soil fertility in terms of alkaline KMnO 4 -N, Olsen-P, NH 4 OAc-K and CaCl 2 -S as well as SOC pools namely, total organic carbon (TOC), Walkley and Black organic carbon (WBC), labile organic carbon (LBC) and microbial biomass carbon (MBC) were maintained under FYM and integrated nutrient management involving FYM and NPK than unfertilized control plot in 0-15 and 15-30 cm soil depths. The highest values of TOC (11.48 g kg −1 ) and WBC (7.86 g kg −1 ) were maintained in FYM treated plot, while the highest values of LBC (1.36 g kg −1 ) and MBC (273 mg kg −1 ) were found in FYM + NPK. The magnitude of change in pools of SOC in sub-surface (15-30 cm) soil was low as compared to the surface soil (0-15 cm). Significant increase in all the pools of SOC in FYM treated plots indicates the importance of application of organic manure like FYM in maintaining organic carbon in soil. Highly strong relationships were exhibited between LBC and MBC with yield, indicating that these pools are more important for nutrient turn-over and their availability to plants than total SOC. Carbon management index revealed that integrated nutrient management could be followed for enhancing crop productivity, nutrient availability and soil carbon pools for long-term. These results conclude that for sustainable crop production and maintaining soil quality, input of organic manure like FYM is of major importance and should be advocated in the nutrient management of intensive cropping system for improving soil fertility and biological properties of soils.
Impact of soil amendments on organic carbon pools under a rice-wheat cropping system
2010
Rice-wheat cropping is the dominant cropping sequence in the Indo-Gangetic plains (IGP) of India. An experiment was conducted to study the impact of continuous application of farmyard manure (FYM) and rice straw (RS), either alone or in conjunction with fertilizer nitrogen (N), under a rice-wheat cropping system on i) total soil organic carbon (SOC) and slow pool C, and ii) stabilization of cumulative input C. Application of FYM, after seven years of rice-wheat cropping cycles, increased total SOC and slow pool C at 0-0.15 m soil depth by 6.7 t/ha and 1.5 t/ha, respectively, with the highest effect when FYM, RS and fertilizer N were applied together. Incorporation of RS increased total SOC by 4.1 t/ha, with an insignificant effect on the slow pool C. There was no significant effect of fertilizer N application on total SOC and slow pool C. The slow pool C was strongly correlated with the total SOC. About 18.5% and 4.2% of the cumulative input C were stabilized as total SOC and slow p...
Studying the dynamics of soil organic carbon (SOC) is important for understanding the carbon stabilization into different pools. Thus, a 25-year old experiment was used to assess the impact of double rice cropping system with addition of organics and grades of fertilization on labile carbon pools and crop yield sustainability in an Inceptisol in southern India. There was significant decrease (p<0.05) in bulk density with increase in the use of organics over control. Green manure applied (in combination with NPK or NPK+farmyard manure) showed greater mineralisable carbon hence, could say greater microbial activity and carbon turnover. The lowest value of microbial quotient (MQ) in the control indicated a poor quality soil with impairment of its capacity for C cycling. The better nutritional environment to microbial population in the soils under balanced fertilization along with organics increased the quotient. The higher respiration quotient (qCO 2) in the control treatment suggested a less efficient use of available carbon by the microbes there.
Environmental Monitoring and Assessment, 2020
A comprehensive study on various pools of soil organic carbon (SOC) under different rice-based cropping systems is necessary for predicting their effect on soil quality through carbon build-up in soil and their impact on global climate change. The present investigation was undertaken to study the longterm effect of six different rice-based cropping systems (continuously followed by farmers > 10 years) on various SOC pools viz., total organic carbon (TOC), oxidizable organic carbon (C oc) and its different fractions [C frac1 (very labile), C frac2 (labile), C frac3 (less labile) and C frac4 (non-labile)], soil microbial biomass carbon (SMBC) and lability index (LI) and SOC stock at the farmer's field of Kakching district under hilly ecosystems of Manipur, India. In every cropping system, all the fractions of C oc were significantly decreased with increasing soil depth. Among all the fractions, C frac4 (non-labile) constituted the largest percentage of TOC for both surface (0-20 cm) and sub-surface (20-40 cm) soil varying from 47.95-58.45% and 55.76-64.83% with average values of 51.87 and 59.73% respectively. Results also revealed that the C frac1 (very labile) of C oc constituted highest (42.79%) percentage of C oc and that of C fract4 constituted highest percentage (55.80%) of TOC. In both soil depths, rice-pea cropping system recorded highest TOC, C oc and SMBC followed by rice-French bean and rice-potato. In surface soil, the lowest TOC, C oc and SMBC were recorded in ricemustard which was statistically at par with rice-cabbage. The SOC stock of both soil layers was also recorded highest in rice-pea. The highest LI of surface soil was recorded in rice-potato which was statistically equal with rice-pea and rice-French bean. Significant correlations among different pools/ fractions of C and with available nutrients indicate their importance in improving soil quality. Long-term combination of rice with the leguminous crops and/or potato enhanced C oc , TOC, SMBC, LI and active pools (C frac1 + C frac2) of rapid turnover rate that may influence the quality and productivity of soil. Long-term cultivation of rice-French bean with high passive C along with good active C and LI is proved to be a good cropping system for sustaining soil and environment by enhancing quality and C reserve of degraded soils of hilly agroecosystem.
International Journal of Current Microbiology and Applied Sciences, 2020
Soil organic matter content and several fractions of soil organic carbon are considered to be sensitive indicator of soil health who on several conditions like cropping choice and management practices. The presence of different soil organic C pool in rice cultivating soils are well documented but thoroughly studied information on relation between soil C status and different rice based cropping managements are not available. Total organic C, water extractable organic C, humus C, microbial biomass C and total carbohydrate analyzed on the soils of long term cultivated rice fields for this study. Three rice based cropping systems like rice-rice, rice-wheat, and rice-fallow from semi-arid climatic zone of west Bengal were chosen for this purpose. After long term cultivation it was found, soils may face 50-60% depletion of TOC in cultivated soils than uncultivated virgin grasslands. WEOC, MBC were considered as most sensitive parameter because of their significant correlation with other parameters and capability of concluding on overall soil health. Both the parameters showed rice-wheat (53% and 27% higher than rice fallow respectively) soil is much more biologically active than others. Total carbohydrate was found higher in rice-rice (80% higher than rice fallow) and humus was found higher ricefallow (76% higher than rice rice) soils, reflecting differential impact on various C pools by different management practice of rice. The correlation found between SOC pools were mostly positive but with varying magnitude. Soil C pool dynamics after long term cultivation affect not only justifies variable physicochemical and biochemical soil properties but also gives a clue for choosing a suitable cropping pattern which may returns with better soil health.
2005
In south Asian countries, production fatigue has been observed as yields which have started declining or stagnating under long-term experiments in multiple cropping systems due to continuous cultivation. We examined the potential impact of continuous cultivation of crops in rotation, and fertilizer and manure application on yield trends, soil organic carbon (SOC) storage, soil quality parameters (active fractions of SOC in particular) and sustainable yield index (SYI). Crop rotations included in the study were: rice-wheat-jute, soybean-wheat and sorghum-wheat system at Barrackpore (Typic Eutrochrept), Ranchi (Typic Haplustalf) and Akola (Typic Haplustert), respectively. Field treatments included unfertilized (control), 100% N, 100% NP, 100% NPK and 100% NPK + FYM. The negative yield trend was observed in unbalanced use of inorganic N and NP application at all the three sites. The positive yield trend was observed in the NPK and NPK + FYM treatments at Ranchi and Akola. However, significantly negative-yield trends were observed in these treatments at Barrackpore under rice-based system. Results showed that the SOC in the unfertilized plot (control) decreased by 41.5, 24.5, and 15.5% compared to initial values in Barrackpore, Ranchi and Akola, respectively, wherein the treatment receiving NPK and NPK + FYM either maintained or improved it over initial SOC content in these sites. The estimated annual C input values in NPK + FYM treatments were 4392, 4159 and 3113 kg ha À1 year À1 in rice-wheat-jute, sorghum-wheat and soybean-wheat system, respectively. Active fractions of SOC, viz., water-soluble carbon and hydrolysable carbohydrates, soil microbial biomass C and N, dehydrogenase and alkaline phosphatase activity, improved significantly with the application of NPK and NPK + FYM. The content of SOC significantly (p 0.05) correlated with SYI and active fractions of SOC, which support better sustainable productivity. Results suggest that current fertilizer recommendations of 100% recommended NPK are adequate for maintaining SOC and its active fractions as www.elsevier.com/locate/fcr Field Crops Research 93 (2005) 264-280