Search

To predict the mineralization of nitrogen(N) in organic amendments in paddy fields, we applied data obtained from incubation experiments under waterlogged conditions by a hierarchical Bayesian model using acid-detergent-soluble organic N (ADSON) as a model input. Each of 20 organic amendments (6 cattle manure composts, 3 swine manure composts, 3 poultry manure composts, 2 oil cakes, 2 rice brans, 1 fish meal, 1 sludge fertilizer, and 2 mixed commercial organic fertilizers) was mixed with paddy soil, and the N mineralization curves obtained after 1, 2, 4, 8, and 12 weeks of waterlogging were incorporated into the model to obtain values of the model parameters ki, α1, and Q10. All model parameters converged with a mean absolute error (MAE) of 0.044 g N kg−1, a root mean square error (RMSE) of 0.060 g N kg−1, and a model efficiency (EF) of 0.96. These values were comparable to or slightly better than those of a previous model for upland soil conditions. Most of the observed values were within the 95% Bayesian prediction interval, indicating that the model performed well with the observed data. Although it is generally believed that livestock manure composts decompose more slowly than organic fertilizers such as oil cake, the livestock manure composts had a large value of the rate constant ki, presumably because of the initial rapid decomposition of the small amounts of organic N present in them. In paddy fields, the soil conditions are aerobic between the application of organic amendments and water entry. In such a case, we propose the use of the upland field model to predict the mineralization of organic N during the period of aerobic soil conditions and of this study's model during the period of waterlogging, subtracting the amount of already mineralized N from the parameters Nin and ADSON. The model devised here is expected to be useful for fertilization design in organic agriculture and in the reduction of the use of inorganic fertilizer. [ABSTRACT FROM AUTHOR]

To identify efficient field management practices for enhanced soil carbon sequestration suited to crop rotation-based Andosol fields in northern Japan, the impacts of a combination of tillage, fertilizer type, and plant residue input on soil carbon sequestration rates were studied in a 4-year field experiment (April 2007 to March 2011). The rates of changes in soil organic carbon over the entire study period were determined by soil carbon stock change and by net ecosystem carbon budget. Across eight field management treatments and two replicates for each treatment, the rates of changes in soil organic carbon determined by net ecosystem carbon budget were positively correlated with the rates determined by soil carbon stock change (r = 0.766,n = 16). The arithmetic means of the rates determined by net ecosystem carbon budget (1.24 Mg C ha−1 year−1) were greater than those determined by soil carbon stock change (−0.18 Mg C ha−1 year−1) because decomposing crop residues and composted cattle manure in soil were included in the calculation of the net ecosystem carbon budget but were excluded in the calculation of soil carbon stock change (decomposing crop residues and composted cattle manure in soil samples were removed by sieving in measuring the soil carbon stock change). Both methods led to the same conclusion that soil carbon sequestration was significantly enhanced by composted cattle manure application and increased input of plant carbon from crop residues and green manure but was not enhanced by reduced tillage. Thepvalues for net ecosystem carbon budget were smaller than those for soil carbon stock change in analysis of variance; therefore, the net ecosystem carbon budget was more sensitive to field management practice than the soil carbon stock change. [ABSTRACT FROM PUBLISHER]

In the context of sustainable soil-quality management and mitigating global warming, the impacts of incorporating raw or field-burned adzuki bean (Vigna angularis(Willd.) Ohwi & Ohashi) and wheat (Triticum aestivumL.) straw residues on carbon dioxide (CO2) and nitrous oxide (N2O) emission rates from soil were assessed in an Andosol field in northern Japan. Losses of carbon (C) and nitrogen (N) in residue biomass during field burning were much greater from adzuki bean residue (98.6% of C and 98.1% of N) than from wheat straw (85.3% and 75.3%, respectively). Although we noted considerable inputs of carbon (499 ± 119 kg C ha–1) and nitrogen (5.97 ± 0.76 kg N ha–1) from burned wheat straw into the soil, neither CO2nor N2O emission rates from soil (over 210 d) increased significantly after the incorporation of field-burned wheat straw. Thus, the field-burned wheat straw contained organic carbon fractions that were more resistant to decomposition in soil in comparison with the unburned wheat straw. Our results and previously reported rates of CO2, methane (CH4) and N2O emission during wheat straw burning showed that CO2-equivalent greenhouse gas emissions under raw residue incorporation were similar to or slightly higher than those under burned residue incorporation when emission rates were assessed during residue burning and after subsequent soil incorporation. [ABSTRACT FROM PUBLISHER]

The total area of abandoned and fallow agricultural fields in Japan has been increasing annually. The change in agricultural land use can alter belowground carbon (C) stocks associated with changes in the types of plant species. The aim of this study was to investigate how the cessation of cultivation influenced the soil C storage in former agricultural fields. The study sites were previously used for rice (Poaceae,Oriza sativaL.) and wheat (Poaceae,TriticumL.) cultivation, and fallow management practices had been in effect for three years under three different conditions: two treatments involved mowing and either leaving the plant residue on the ground or removing the plant residue, while the third treatment involved simply abandoning the field. We found that the former paddy site invaded by rhizomatous perennial grasses had significantly higher soil C storage compared to former upland fields that was dominated by annual grass species. The cessation of cultivation increased soil C storage by about 1.3 times in former paddies, and decreased the content by 0.83–0.91 times in former uplands. The three-year total belowground production was 2.0–4.7 times greater in former paddies than former uplands for each management condition, suggesting that lower C input from the annual grasses caused a loss in soil C at the upland fields. Aboveground biomass removal of the perennial grasses strongly reduced C input, whereas the C input from their high belowground production led to the significant increases of soil C storage near the surface of the former paddies. Our studies indicate that high belowground productivity of perennial grasses can increase soil C storage after the cessation of cultivation. [ABSTRACT FROM PUBLISHER]

In the context of their role in global warming, nitrous oxide (N2O) emissions from agricultural soil under different management practices were studied in Hokkaido, northern Japan. To assess the impacts of reduced tillage, composted cattle manure-based fertilization and amendments with crop residues and green manure on N2O emissions from soil, a field experiment was conducted under a four-year crop rotation on a well-drained Andisol. The crop rotation included potato (Solanum tuberosumL.) or sweet corn (Zea maysL.), winter wheat (Triticum aestivumL.), sugar beet (Beta vulgarisL. subsp.vulgaris) and soybean (Glycine max(L.) Merr.). The cumulative N2O emissions for the four-year study period differed widely (0.33 to 4.90 kg N ha−1), depending on the treatments imposed, being the greatest for a combination of conventional moldboard plow tillage, composted cattle manure-based fertilization and increased plant residue input, and the lowest for a combination of conventional tillage, chemical fertilizer-based fertilization and normal plant residue input treatments. The cumulative N2O emissions under reduced tillage were all small, irrespective of fertilization and plant residue input treatments. Composted cattle manure-based fertilization (P ≤ 0.01) and increased plant residue input (P ≤ 0.01) significantly increased cumulative N2O emissions. Tillage showed a significant interaction with fertilization and plant residue input, indicating that N2O emissions were enhanced when composted cattle manure, crop residues and green manure were incorporated by conventional tillage. In the present study, the N2O emission factors for chemical fertilizer, composted cattle manure and crop residues were 0.26 ± 0.44, 0.11 ± 0.16 and −0.03 ± 0.52%, respectively, all much lower than the country-specific emission factor for Japan's well-drained soils (0.62%) and the default emission factor used in the IPCC guideline (1%). [ABSTRACT FROM PUBLISHER]

Soil carbon sequestration in agricultural lands has been deemed a sustainable option to mitigate rising atmospheric CO2 levels. In this context, the effects of different tillage and C input management (residue management and manure application) practices on crop yields, residue C and annual changes in total soil organic C (SOC) (0–30 cm depth) were investigated over one cycle of a 4-year crop rotation (2003–2006) on a cropped Andisol in northern Japan. For tillage practices, the effects of reduced tillage (no deep plowing, a single shallow harrowing for seedbed preparation [RT]) and conventional deep moldboard plow tillage (CT) were compared. The combination of RT, residue return and manure application (20 Mg ha−1 in each year) increased spring wheat and potato yields significantly; however, soybean and sugar beet yields were not influenced by tillage practices. For all crops studied, manure application enhanced the production of above-ground residue C. Thus, manure application served not only as a direct input of C to the soil, but the greater crop biomass production engendered enhanced subsequent C inputs to the soil from residues. The SOC contents in both the 0–5 cm and 5–10 cm layers of the soil profile were greater under RT than under CT treatments because the crop residue and manure were densely incorporated into the shallow soil layers. Comparatively, neither tillage nor C input management practices had significant effects on annual changes in SOC content in either the 10–20 cm or 20–30 cm layers of the soil profile. When soil C sequestration rates, as represented by annual changes in total SOC (0–30 cm), were assessed on a total soil mass basis, ananova showed that tillage practices had no significant effect on total C sequestration, but C input management practices had significant positive effects ( P ≤ 0.05). These results indicate that continuous C input to the soil through crop residue return and manure application is a crucial practice for enhancing crop yields and soil C sequestration in the Andisol region of northern Japan. [ABSTRACT FROM AUTHOR]

To assist assignment of bacterial phylogeny based on multiple enzyme restriction fragment length polymorphism (MERFLP) analysis, new programs were developed; one program was used to construct reference database of theoretical multiple enzyme restriction fragment (MERF) data, which were edited from DNA sequence of various kinds of bacteria; the other program was used to search the theoretical MERF having the highest similarity to the measured MERF based on pairwise distance according to Nei and Li. Using proteolytic bacteria (96 strains) isolated from various field soils and 25 reference strains, the factors that affected accurate phylogenetic estimation were evaluated. Bacterial strains from the genus Bacillus were successfully separated into species using the MERF with HaeIII and HhaI as the restriction enzymes. Genera Xanthomonas, Pseudomonas, and Alcaligenes were affiliated with the corresponding genus, but precise affiliation under genus level was not always possible. Differentiation among genera in the Enterobacteriaceae may be possible using the other restriction enzymes ( HhaI , RsaI and ScrF1). The method was found to be useful for the analysis of bacterial flora because the differentiation, grouping and phylogeny assignment of bacteria, including various genera, were easily accomplished without preliminary information. Most (97.8%) of the proteolytic bacteria isolated from field soils applied with chemical fertilizer or no fertilizer were affiliated with Bacillus spp., whereas the ratios were low in those isolated from field soils applied with liquid livestock feces. [ABSTRACT FROM AUTHOR]

To assess their impacts on net global warming, total greenhouse gas emissions (mainly CO2, N2O and CH4) from agricultural production in arable land cropping systems in the Tokachi region of Hokkaido, Japan, were estimated using life cycle inventory (LCI) analysis. The LCI data included CO2 emissions from on-farm and off-farm fossil fuel consumption, soil CO2 emissions induced by the decomposition of soil organic matter, direct and indirect N2O emissions from arable lands and CH4 uptake by soils, which were then aggregated in CO2-equivalents. Under plow-based conventional tillage (CT) cropping systems for winter wheat, sugar beet, adzuki bean, potato and cabbage, on-farm CO2 emissions from fuel-consuming operations such as tractor-based field operations, truck transportation and mechanical grain drying ranged from 0.424 Mg CO2 ha−1 year−1 for adzuki bean to 0.826 Mg CO2 ha−1 year−1 for winter wheat. Off-farm CO2 emissions resulting from the use of agricultural materials such as chemical fertilizers, biocides (pesticides and herbicides) and agricultural machines were estimated by input–output tables to range from 0.800 Mg CO2 ha−1 year−1 for winter wheat to 1.724 Mg CO2 ha−1 year−1 for sugar beet. Direct N2O emissions previously measured in an Andosol field of this region showed a positive correlation with N fertilizer application rates. These emissions, expressed in CO2-equivalents, ranged from 0.041 Mg CO2 ha−1 year−1 for potato to 0.382 Mg CO2 ha−1 year−1 for cabbage. Indirect N2O emissions resulting from N leaching and surface runoff were estimated to range from 0.069 Mg CO2 ha−1 year−1 for adzuki bean to 0.381 Mg CO2 ha−1 year−1 for cabbage. The rates of CH4 removal from the atmosphere by soil uptake were equivalent to only 0.020–0.042 Mg CO2 ha−1 year−1. From the difference in the total soil C pools (0–20 cm depth) between 1981 and 2001, annual CO2 emissions from the CT and reduced tillage (RT) soils were estimated to be 4.91 and 3.81 Mg CO2 ha−1 year−1, respectively. In total, CO2-equivalent greenhouse gas emissions under CT cropping systems in the Tokachi region of Hokkaido amounted to 6.97, 7.62, 6.44, 6.64 and 7.49 Mg CO2 ha−1 year−1 for winter wheat, sugar beet, adzuki bean, potato and cabbage production, respectively. Overall, soil-derived CO2 emissions accounted for a large proportion (64–76%) of the total greenhouse gas emissions. This illustrates that soil management practices that enhance C sequestration in soil may be an effective means to mitigate large greenhouse gas emissions from arable land cropping systems such as those in the Tokachi region of northern Japan. Under RT cropping systems, plowing after harvesting was omitted, and total greenhouse gas emissions from winter wheat, sugar beet and adzuki bean could be reduced by 18%, 4% and 18%, respectively, mainly as a result of a lower soil organic matter decomposition rate in the RT soil and a saving on the fuels used for plowing. [ABSTRACT FROM AUTHOR]