Amount Of Organic Amendments Research Articles

Effects of long-term application of inorganic fertilizer and organic amendments on the amounts of fractionated soil organic carbon and their determining factors in paddy fields

ABSTRACT To investigate how the long-term application of inorganic fertilizer and organic amendments affects the accumulation of organic matter in physico-chemically fractionated components in paddy soils and how the accumulation is determined by soil properties and anthropogenic carbon input, we studied the effect of variable management of inorganic fertilizer and organic amendments for > 50 years on the amounts of accumulated soil organic carbon (SOC) in fractionated components in three paddy fields. SOC was fractionated into four components based on their physical and chemical properties: (1) light fraction (LF) derived from plant residues, (2) heavy fraction (HF) containing stable aggregates, (3) oxidizable fraction (OxF) and (4) non-oxidizable fraction (NOxF) forming organo-mineral complexes with fine-textured minerals. On average, the amount and percentage of accumulated C in the four fractions were as follows: OxF (6.63 gC kg−1 soil, 46%) > NOxF (5.32, 35) > LF (1.68, 12) > HF (1.12, 7.2), suggesting about 80% of SOC was in fine, stable fractions. The amount of accumulated C in all fractions increased slightly with the application of inorganic fertilizer, while it increased considerably with the use of organic amendments. In addition, the application of fertilizers and amendments raised the proportion of C content in LF and HF, which are labile and related to soil fertility. Stepwise multiple regression analysis using two principal component analysis scores of soil properties and anthropogenic C input further revealed that the labile fractions (LF and HF) were more strongly determined by the management of fertilizers and amendments, while the stable fractions (OxF and NOxF) were more strongly determined by soil-specific properties, mainly the amorphous nature of the soil. These results indicate that the use of certain amounts of organic amendments would be recommended to carry out rational management to improve soil fertility and C sequestration in paddy fields, with the application of amorphous minerals as an additional option.

Sensitivity analysis of agricultural inputs for large-scale soil organic matter modelling

The dynamics of Soil Organic Matter (SOM) and its relation to the carbon and nitrogen cycle affect many environmental problems (e.g. climate change, food security and water quality). The development of adaptation strategies requires model predictions, but for the necessary large-scale SOM dynamic studies, the quality of the input data is often limiting the reliability of the results.So we performed a uncertainty and sensitivity analysis at different sites of the federal state of Saxony, Germany, and assessed the importance of aggregated agricultural data, namely organic amendments, crop yields, area share of by-product incorporation, area share of conservation tillage and initial soil organic carbon (SOC) concentration (p_oram, p_yield, p_bp, p_cons and p_soc respectively) on the result uncertainty by assuming an uniform error of ±10%. The agricultural data was regionalized from 717 long-term observation fields throughout the study region.We assessed the uncertainties of relative SOC stock change (ΔCrel) and total nitrogen mineralisation from the organic matter (OM-Nmin) and explored the changing sensitivities over the model period (1998–2014).Our results show that p_soc was the most important source of uncertainty for all sites of this study. For ΔCrel, it is over the whole time constantly the by far most sensitive input parameter, with p_bp being the only factor of agricultural practice with some substantial influence on almost all sites. In the mountainous regions, p_cons ranks equal to p_bp, while for the sandy heathlands, none of them mark a substantial influence besides p_soc.For OM-Nmin, p_soc loses its importance over time, being outranked by p_oram in the heathlands after 8 years and in the mountainous regions after 13 years. p_oram furthermore places second for all others but one other region, where p_cons is slightly more important. We therefore see the initial carbon content, the share of by-product removal, and the amount of organic amendments as those factors, where improved data quality would bring the highest effect to reduce the uncertainty in regional SOM modelling.

Organic Residue Amendments to Modulate Greenhouse Gas Emissions From Agricultural Soils.

Organic fertilizers have been shown to stimulate CH4 uptake from agricultural soils. Managing fertilizer application to maximize this effect and to minimize emission of other greenhouse gasses offers possibilities to increase sustainability of agriculture. To tackle this challenge, we incubated an agricultural soil with different organic amendments (compost, sewage sludge, digestate, cover crop residues mixture), either as single application or in a mixture and subjected it to different soil moisture concentrations using different amounts of organic amendments. GHG fluxes and in vitro CH4 oxidation rates were measured repeatedly, while changes in organic matter and abundance of GHG relevant microbial groups (nitrifiers, denitrifiers, methanotrophs, methanogens) were measured at the end of the incubation. Overall the dynamics of the analyzed GHGs differed significantly. While CO2 and N2O differed considerably between the treatments, CH4 fluxes remained stable. In contrast, in vitro CH4 oxidation showed a clear increase for all amendments over time. CO2 fluxes were mostly dependent on the amount of organic residue that was used, while N2O fluxes were affected more by soil moisture. Several combinations of amendments led to reductions of CO2, CH4, and/or N2O emissions compared to un-amended soil. Most optimal GHG balance was obtained by compost amendments, which resulted in a similar overall GHG balance as compared to the un-amended soil. However, compost is not very nutrient rich potentially leading to lower crop yield when applied as single fertilizer. Hence, the combination of compost with one of the more nutrient rich organic amendments (sewage sludge, digestate) provides a trade-off between maintaining crop yield and minimizing GHG emissions. Additionally, we could observe a strong increase in microbial communities involved in GHG consumption in all amendments, with the strongest increase associated with cover crop residue mixtures. Future research should focus on the interrelation of plants, soil, and microbes and their impact on the global warming potential in relation to applied organic amendments.

Global estimations of the inventory and mitigation potential of methane emissions from rice cultivation conducted using the 2006 Intergovernmental Panel on Climate Change Guidelines

The Intergovernmental Panel on Climate Change (IPCC) regularly publishes guidelines for national greenhouse gas inventories and methane emission (CH4) from rice paddies has been an important component of these guidelines. While there have been many estimates of global CH4 emissions from rice fields, none of them have been obtained using the IPCC guidelines. Therefore, we used the Tier 1 method described in the 2006 IPCC guidelines to estimate the global CH4 emissions from rice fields. To accomplish this, we used country‐specific statistical data regarding rice harvest areas and expert estimates of relevant agricultural activities. The estimated global emission for 2000 was 25.6 Tg a−1, which is at the lower end of earlier estimates and close to the total emission summarized by individual national communications. Monte Carlo simulation revealed a 95% uncertainty range of 14.8–41.7 Tg a−1; however, the estimation uncertainty was found to depend on the reliability of the information available regarding the amount of organic amendments and the area of rice fields that were under continuous flooding. We estimated that if all of the continuously flooded rice fields were drained at least once during the growing season, the CH4 emissions would be reduced by 4.1 Tg a−1. Furthermore, we estimated that applying rice straw off season wherever and whenever possible would result in a further reduction in emissions of 4.1 Tg a−1 globally. Finally, if both of these mitigation options were adopted, the global CH4 emission from rice paddies could be reduced by 7.6 Tg a−1. Although draining continuously flooded rice fields may lead to an increase in nitrous oxide (N2O) emission, the global warming potential resulting from this increase is negligible when compared to the reduction in global warming potential that would result from the CH4 reduction associated with draining the fields.

Bioremediation of diesel-contaminated soil with composting

The major objective of this research was to find the appropriate mix ratio of organic amendments for enhancing diesel oil degradation during contaminated soil composting. Sewage sludge or compost was added as an amendment for supplementing organic matter for composting of contaminated soil. The ratios of contaminated soil to organic amendments were 1:0.1, 1:0.3, 1:0.5, and 1:1 as wet weight basis. Target contaminant of this research was diesel oil, which was spiked at 10,000 mg/kg sample on a dry weight basis. The degradation of diesel oil was significantly enhanced by the addition of these organic amendments relative to straight soil. Degradation rates of total petroleum hydrocarbons (TPH) and n-alkanes were the greatest at the ratio of 1:0.5 of contaminated soil to organic amendments on wet weight basis. Preferential degradation of n-alkanes over TPH was observed regardless of the kind and the amount of organic amendments. The first order degradation constant of n-alkanes was about twice TPH degradation constant. Normal alkanes could be divided in two groups (C10–C15 versus C16–C20) based on the first order kinetic constant. Volatilization loss of TPH was only about 2% of initial TPH. Normal alkanes lost by volatilization were mainly by the compounds of C10 to C16. High correlations ( r=0.80–0.86) were found among TPH degradation rate, amount of CO 2 evolved, and dehydrogenase activity.

Changes in the organic matter mineralization rates of an arid soil after amendment with organic wastes

This study examined the changes in organic matter mineralization when six amendment rates of municipal solid waste, sewage sludge, and compost were added to an arid soil. Short‐time incubation assays were carried out in which the amount of CO2 emitted was measured. The kinetic and mineralization constants of the organic matter were studied, as was the influence, of this amendment on the soil organic matter content. Potentially mineralizable C (C0) in the municipal solid waste‐amended soil was significantly higher than in the soil amended by sewage sludge and compost and it increased as the amendment rate of compost and sewage sludge increased. There was no direct relation between the increase in organic matter decomposition rate and the amount of organic amendments that were applied to the soil. The CO2 loss/total organic carbon (CO2 loss/TOC) ratio in the soils amended with fresh organic waste was significantly higher than in that amended with compost. The CO2 loss/TOC ratio also differed with amendment rate between fresh and composted wastes. The ratio rose slightly as the amendment rate of fresh wastes increased up to 2%, after which it stabilized, whereas it decreased as the amendment rate increased in the soils amended with compost. Linear fittings were made of the CO2 evolved as a function of dose for the different sampling times. The carbon mineralized increased in all treatments, more so in the soils amended with fresh wastes than in those amended with compost. The organic amendments resulted in a priming effect that was more pronounced during the first days of incubation and differs according to the nature of the material added.