Effect Of Rice Straw Incorporation Research Articles

The effects of adding exogenous lignocellulose degrading bacteria during straw incorporation in cold regions on degradation characteristics and soil indigenous bacteria communities.

Low temperature is one of the bottleneck factors that limits the degradation of straw during rice straw incorporation. Determining strategies to promote the efficient degradation of straw in cold regions has become a highly active research area. This study was to investigate the effect of rice straw incorporation by adding exogenous lignocellulose decomposition microbial consortiums at different soil depths in cold regions. The results showed that the lignocellulose was degraded the most efficiently during straw incorporation, which was in deep soil with the full addition of a high-temperature bacterial system. The composite bacterial systems changed the indigenous soil microbial community structure and diminished the effect of straw incorporation on soil pH, it also significantly increased rice yield and effectively enhanced the functional abundance of soil microorganisms. The predominant bacteria SJA-15, Gemmatimonadaceae, and Bradyrhizobium promoted straw degradation. The concentration of bacterial system and the depth of soil had significantly positive correlations on lignocellulose degradation. These results provide new insights and a theoretical basis for the changes in the soil microbial community and the application of lignocellulose-degrading composite microbial systems with straw incorporation in cold regions.

Soil available potassium affected by rice straw incorporation and potassium fertilizer application under a rice–oilseed rape rotation system

AbstractData from 147 field trials were collected to study the influence of straw incorporation on soil potassium (K) under an intensive rice–oilseed rape rotation system, while pot experiments were conducted to evaluate the effects of rice straw incorporation on soil K availability. A significant correlation was observed between the soil available K and the relative yield (RRY) and the relative K uptake (RKU) of oilseed rape, with R2 values ranging from 0.07 to 0.08 and from 0.10 to 0.11, respectively, when data were fitted to a logarithmic equation model. In approximately 30% of trials, RRY reached 90%, while soil test available K values were below the critical limit, indicating that soil K values at the time of sampling (within 1 week of rice harvest) underestimated the actual soil K supply capacity. The pot experiment results showed that soil available K was affected by straw incorporation and soil type in the fallow period. The NH4OAc‐K and NaBPh4‐K concentrations of soils increased at first, and then, plateaued after 28 days. Straw incorporation significantly influenced the critical soil K concentration, which is important for making accurate K fertilizer recommendation. These results suggested that straw K should be seriously considered in making K fertilizer recommendations. Extending the sampling time from 1 to 3 weeks after the harvesting of rice to stabilize the effects of straw incorporation may help achieve a more accurate evaluation of soil available K.

Modeling a long-term effect of rice straw incorporation on SOC content and grain yield in rice field

ABSTRACTThe long-term effects of rice straw incorporation on soil organic carbon (SOC) content and rice yield were evaluated from rice cultivation with different treatments: no rice straw (control), rice straw (RS), and rice straw compost (RSC) as a main-plots; five levels of nitrogen (N) fertilizer application: 0, 100, 150, 200, and 250 of N (kg ha−1) as a sub-plots. The denitrification and decomposition (DNDC) model was employed to simulate changes in SOC content and rice grain yield over 35 years. Additionally, scenario analysis on continuous or discontinuous RS incorporation in rice fields was conducted using the DNDC model. The long-term results indicated that RS and RSC treatments played a crucial role in increasing grain yields by 9% and 11% due to the increased SOC contents compared to control treatment. The validated DNDC model on SOC contents and yields showed a good agreement between the observed and simulated values based on the normalized root mean square errors. The model predicted a rapid decline of SOC contents without RS incorporation. Results suggested that incorporating rice straw or amending manure to paddy soils is a preferred practice for maintaining SOC contents.

Effects of rice straw incorporation and N fertilizer on ryegrass yield, soil quality, and greenhouse gas emissions from paddy soil

Ryegrass is usually rotated with rice in southern China. The influences of returning ryegrass residues on rice yield and soil dynamics have been studied extensively, but little is known about the effects of returning rice straw on ryegrass growth and soil variations. We investigated the effect of straw incorporation and the N fertilizer rate on the ryegrass yield, soil quality, and CO2 and N2O dynamics from soils planted with ryegrass. Irrespective of the incorporation rate, N fertilizer promoted ryegrass yield. In comparison to moderate incorporation treatments, high incorporation lowered the ryegrass yield in the low N fertilizer treatments, whereas high straw input increased the yield in the high N treatments. When low N fertilizer was applied, the soil phosphatase, β-glucosidase, and sucrase of straw incorporation treatments were significantly higher than those of non-straw incorporation treatments. Nevertheless, catalase, phosphatase, and β-glucosidase showed no significant differences among straw incorporation treatments in the high N fertilizer groups. In the low N fertilizer treatments, the high incorporation rate increased cumulative CO2 and N2O emissions. However, with low N application, compared with non-straw incorporation treatments, the moderate incorporation had no effect on the cumulative CO2 emissions/ryegrass yield but significantly reduced the cumulative N2O emissions/ryegrass yield. These results suggested that moderate straw incorporation in combination with low N fertilizer could enhance soil activity and benefit both the mitigation of greenhouse gas emissions and forage yield.

Discrepant responses of methane emissions to additions with different organic compound classes of rice straw in paddy soil

Crop straw incorporation has become a prevailing agricultural practice that guarantees the food production and security. There is a significant body of work on the effects of straw incorporation on the methane (CH4) emissions in paddy fields. However, it is unclear whether there are diverse links between CH4 emission dynamics and incorporations of different organic compound classes of straw to paddy fields. In this study, soil incubations were conducted to assess the respective effect of incorporations of hydrolysable amino acid (HAA), dilute-acid extractable carbohydrate (DAC), lipid and acid-insoluble organic matter (AIOM) fractions of rice straw on the CH4 emission in paddy soil. It is revealed that incorporations of HAA and DAC fractions exert the greatest intensities to stimulate the CH4 emissions, which mainly takes place in the early period of incubation; on contrary, the incorporation of lipid fraction exerts the lowest intensity and mainly takes place in the late period. The pattern of CH4 emission after incorporation of AIOM fraction occurs peaks both in the early and late periods of incubation. Our findings highlight that the time of occurrence and intensity of effects of rice straw incorporation on CH4 emissions vary significantly depending on the different organic compound classes of rice straw, which may be key to proposing a promising management strategy for mitigating CH4 emissions in paddy fields in the context of straw incorporation.

Effect of rice straw incorporation on methane emission and rice yields from rice cropping system by DNDC-Rice model

This study applied the DNDC-Rice model and simulated against field observation in Thailand. Simulated CH4 emission data shown acceptable results compared to field observation recorded. Rice straw incorporation into field plays important role on CH4 emission by continuous increase soil organic carbon as well as soil iron contents, consequently to low soil Eh which is suitable for CH4 production. Higher amount of rice straw applied induces higher CH4 emission vice versa. Therefore, reduction of rice straw amount incorporation into soil is possible practical mitigation options for CH4 production.

Effect of rice straw incorporation on methane emission and rice yields from rice cropping system by DNDC-Rice model

This study applied the DNDC-Rice model and simulated against field observation in Thailand. Simulated CH4 emission data shown acceptable results compared to field observation recorded. Rice straw incorporation into field plays important role on CH4 emission by continuous increase soil organic carbon as well as soil iron contents, consequently to low soil Eh which is suitable for CH4 production. Higher amount of rice straw applied induces higher CH4 emission vice versa. Therefore, reduction of rice straw amount incorporation into soil is possible practical mitigation options for CH4 production.

Effects of rice straw incorporation on active soil organic carbon pools in a subtropical paddy field

Understanding the dynamics of soil organic carbon (SOC) in response to changing environment and management practices is crucial for minimizing the climatic impacts of rice agriculture. This study examined the effects of rice straw incorporation on total SOC, active SOC fractions, and carbon pool management index (CPMI) in a subtropical paddy field in China. The straw collected after harvesting the early and late paddy was incorporated immediately into the top 10cm soil at a rate of 3.3Mgha−1 and the top 40cm soil samples in the triplicate treatment, control and reference plots were analyzed for the concentrations of total SOC and four other active SOC fractions at the end of the early and late seasons. The concentrations of total soil organic carbon (SOC), light fraction organic carbon (LFOC), dissolved organic carbon (DOC), and microbial biomass carbon (MBC) were significantly (P<0.05) higher in the straw application plots than in the controls by 7.1–128.6% for both the early and late paddy season. In general, significant and positive correlations were observed between SOC, DOC, LFOC, MBC and labile organic carbon (LOC) in the treatment and control plots for both early and late paddy (r=0.60–0.96, P<0.05). Moreover, there were significant and positive correlations of total SOC and active SOC fractions with both soil water content (r=0.69–0.94, P<0.01) as well as total soil nitrogen content (r=0.69–0.99, P<0.05). Straw incorporation significantly increased CPMI and other active soil organic carbon pools in the early paddy field (P<0.05), but had no significant effects on CPMI in the late paddy field. It is therefore better to incorporate straw residues in the aerobic condition during the early paddy season in order for rice to benefit from an increased CPMI.

Effects of rice straw incorporation and tillage depth on soil puddlability and mechanical properties during rice growth period

Soil puddlability, a measure of susceptibility of soil to puddling, affects regeneration of soil structure during the rice growth period, but the intrinsic controlling factors are unclear. It was hypothesized that rice straw incorporation and tillage depth influence soil puddlability and soil mechanical and hydraulic properties during the rice growth period as they influence soil organic carbon (SOC) in the plough layer. Using a three-year experiment, the objectives of this study were (1) to determine the effects of rice straw incorporation and tillage depth on root growth traits, sinkage resistance after puddling, and tensile strength, shrinkage capacity, water retention curve and penetration resistance during the rice growth period, and (2) to determine whether mechanical properties from puddling tillage, through the rice growth period, to harvest are correlated with SOC concentration. Rice straw was incorporated partially (C1) and fully (C2) to different depths of plough layer by shallow tillage (ST) and deep tillage (DT). Compared with no rice straw incorporation (C0), rice straw incorporation decreased the sinkage resistance after puddling (C2<C1<C0) and increased SOC concentration and aggregate stability. Shallow tillage increased the penetration resistance more than deep tillage irrespective of rice straw incorporation. The difference in tensile strength and total porosity were small among the rice incorporation treatments at the 1st drainage (C2≥C1≥C0), but became more profound with increasing number of drainage because the tensile strength and total porosity decreased in C0, increased in C2, particularly under ST. The root weight was lower, and the root length was longer in C1 than in C2 particularly at the deeper depth of the plough layer under ST, suggesting the impedance of root growth due to higher sinkage and penetration resistances. SOC concentration was weakly correlated with the sinkage and penetration resistances and the tensile strength after the 1st drainage, but not with the tensile strength after the 2nd and 3rd drainages. In conclusion, rice straw incorporation is important to maintain SOC and then improve soil puddlability and the recovery of pore structure during the rice growth period.

The effect of rice straw incorporation into paddy soil on carbon sequestration and emissions in the double cropping rice system

Soil organic carbon (SOC) sequestration, methane emission, and the net carbon sink represented by rice straw incorporated into soil (RIS) were studied using long-term experimentation with rice straw incorporated into soil (LRIS) and short-term experimentation with different patterns of rice straw incorporated into soil (SPRIS). Soil organic carbon could be improved by RIS combined with soil ploughing. The increased rate of SOC deposition per cultivated layer was 0.10 t C ha(-1) for 2.625 t ha(-1) straw incorporated each season in LRIS and 0.36 t C ha(-1) for 4.5 t straw ha(-1) season(-1) incorporated in SPRIS; the apparent SOC conversion by rice straw (stubble) was reduced as the amount of incorporated straw increased. However, RIS methane emission from paddy fields also significantly exacerbated the CH(4) emission flux observed during the early and late rice growing seasons, which was increased by 75.0% (P < 0.01) and 251.5% (P < 0.01), respectively, compared with combined application of nitrogen, phosphorus and potassium fertiliser (NPK). The apparent methane conversion of straw was almost uniform with a similar rice yield and soil cultivating mode. Among the patterns of RIS, methane emission was significantly reduced under straw covering untilled land, and this property led to the lowest apparent methane conversion. RIS with ploughing and tilling resulted in negative carbon sequestration because of increased methane emissions. A combined NPK application with only rice stubble incorporation may be sustainable for a higher rice yield, but this approach has a reduced rate of negative carbon sequestration in the paddy field. Straw covering with no tillage was the best measure to realise high yield and low carbon emission for RIS.

Effect of Rice Straw Incorporation on Phytotoxicity of Isoxaflutole to an Exotic Weed Phalaris minor Retz.

Phalaris minorRetz. is a major exotic annual weed in the wheat (Triticum aestivum L.) crop. Unharvested rice (Oryza sativa L.) straw, unburned and burned, is often incorporated in the field prior to cultivating wheat. Isoxaflutole (Balance), a pre-emergent systemic soil applied herbicide, has potential to control P. minor. Glasshouse experiments were conducted to determine the phytotoxicity of isoxaflutole defined by reductions in relation to shoot length of P. minor when grown in unamended soil or soil amended with unburned or burned rice straw. A 120 g soil was amended with 0, 1, 2 and 4 g of unburned or burned rice straw, and placed in 150 mL styrofoam pots. Appropriate amount of isoxaflutole (75% active ingredient, ai) was added to pots to get final concentration of 0, 7.5, 30, 60 and 120 μg ai/pot. Unamended soil and soil amended with unburned or burned rice straw were analyzed for pH and organic matter; two important determinants of isoxaflutole activity. Results indicate a significant reduction in shoot length of P. minor when grown in soil treated with isoxaflutole at 30, 60 or 120 μg ai/pot. Inhibition in the shoot length of P. minor was observed when soil amended with unburned straw was treated with isoxaflutole at 7.5 and 30 μg ai/pot compared with unamended soil treated with similar amounts of isoxaflutole. No significant change in isoxaflutole toxicity was observed when soil amended with unburned straw was treated with isoxaflutole at 60 and 120 lg ai/pot compared with unamended soil treated with similar amounts of isoxaflutole. Isoxaflutole phytotoxicity to P. minor shoot length was eliminated when soil amended with burned straw was treated with isoxaflutole at 7.5 and 30 μg ai/pot. P. minor shoot length was greater when soil amended with burned straw was treated with isoxaflutole at 60 and 120 μg ai/pot relative to herbicide-treated unamended soils. We conclude that incorporation of burned rice straw greatly reduces the phytotoxicity of isoxaflutole toP. minor.

Effect of Rice Straw Incorporation on Rice Plant Growth and Nutrition1

AbstractRice (Oryza sativa L.) straw disposal by soil incorporation may have adverse effects on subsequent rice seedling growth from toxic anaerobic decomposition products and temporary immobilization of the soil mineral N. Glasshouse and laboratory studies were conducted to study the problem under conditions of direct sowing of rice.Samples of a typical rice soil, Sacramento clay, which is a very fine, montmorillonitic thermic Vertic Hapiquall, were collected. Rice straw in amounts of 0, 0.25, and 0.5% was added to soils which were incubated aerobically for 0, 15, and 30 days in a glasshouse plant growth experiment, and for 0 and 20 days in preparation for a laboratory soil incubation experiment. Nitrogen was applied at the rate of 50 ppm in the glasshouse experiment and 50, 75, and 100 ppm in the laboratory study. N was added after aerobic incubation and subsequently rice was grown for 21 days to measure seeding growth effects. The glasshouse experiment with rice cultivar ‘Earlirose’ also evaluated the production of acetic, propionic, and butyric acids, while the laboratory soil incubation experiment was for N transformation data.The results clearly indicate that when soil and rice straw were not incubated prior to planting rice seedlings, applied N was immobilized, causing inhibition of plant growth and low N content of plants. When rice straw was incubated in soil for 15 to 30 days before planting seedlings, N immobilization was reduced and plant growth was promoted. Nitrogen immobilization was observed to be the principal cause of inhibition of plant growth from added rice straw. Organic acids (acetic and propionic) were produced in amounts considered to be below the toxic concentration of plants. Butyric acid was not found in the soil extracts.