Rice Straw Application Research Articles

Peningkatan Produksi Tanaman Padi Sawah (Oryza Sativa L.) dengan Beberapa Jenis Mulsa dan Beberapa Varitas Pada Metode System of Rice Intensification (SRI)

The study was conducted in the village of Purwodadi, Padangsidimpuan City. The purpose of this study was to examine the increase in production of lowland rice (Oryza sativa L.) in the System Of Rice Intensification method. This experiment uses a Split plot design in a RAK pattern with two factors. The main factor is lowland rice variety consisting of three treatment levels, namely Aryze H6444 variety, Situ Bagendit variety, and Siganteng variety. The subplot factor is the use of mulch which consists of four treatment levels namely rice straw, rice husk, tithonia, and black plastic mulch. Siganteng variety with plastic mulch application showed the highest and lowest panicle lengths were found in the interaction between Aryze H6444 Gold variety and rice husk mulch application. Siganteng variety with mulch application of rice straw showed the highest average number of unprocessed rice. The highest planted fresh grain weight in Siganteng Variety interaction with rice straw mulch was not significantly different from the interaction of Siganteng variety with rice husk mulch. The highest 1000 grain weight was found in the interaction between Siganteng varieties and rice husk mulch. The highest dry weight of grain per plant was found in the interaction of Siganteng varieties with plastic mulch. The highest production potential is found in the interaction of Siganteng varieties with plastic mulch which shows an average of 16.85 tons/ha. The lowest average is found in the interaction of Aryze H6444 Gold variety with tithonia mulch which shows an average of 7.15 tons/ha. Keywords: mulch, variety, system of rice intensification

Effects of Rice Straw Addition on Methanogenic Archaea and Bacteria in Two Paddy Soils

Rice straw (RS) returning has an important effect on CH4 emission in rice paddy soil. In the present study, two paddy soil types from Jiangxi (JX) and Guangdong (GD), respectively, with different amounts of added RS were incubated through microcosmic anaerobic incubation experiments to investigate the responses of methanogenic archaea and bacteria communities after relatively long-term incubation. The different amounts of added RS affected methanogenic archaea community structures in the JX soil to some extent but did not affect the GD soil. The mcrA gene copy number increased with an increase in RS amount in both soils. Under the same amount of RS, the copy number of this gene in the JX soil was greater than that in the GD soil. In addition, significant positive correlations were shown between the RS amount and the copy number of the mcrA gene, and the response of the copy number was more sensitive to the RS amount in the JX soil. Obvious differences in methanogenic archaea community structures were shown between two soils. Methanosarcinaceae, Methanocellaceae, Methanomicrobiaceae, Methanobacteriaceae, and unknown microorganism (494 bp) were detected in the JX soil, and Methanobacteriaceae, Methanosarcinaceae, and Methanocellaceae were observed in the GD soil. The bacterial communities exhibited obvious differences between the two soil types after 180 days of incubation. The bacterial diversity in the GD soil was higher than that in the JX soil, although the amounts of dominant bacteria in the JX soil, including Bacillus, Desulfovirgula, Thermosporothrix, Acidobacteria/Gp1, Acidobacteria/Gp3, and Ktedonobacter, were higher than those of the GD soil, including Longilinea, Acidobacteria/Gp6, Bellilinea, and Thermosporothrix. RS application promoted the growth of methanogenic archaea as important substrates. Moreover, different structures of methanogens and bacteria were shown between the two soil types after relatively long-term incubation.

Application of rice straw as biosorption for removal of dyeing aqueous solution and for improving the fastness property of dyed fabric

Fabric dyeing industry has been widely located throughout Thailand and the treatment of polluted water after dyeing process has been a primary focus. The objectives of this study were to study on factors affecting treated (acidic and alkaline) and non-treated rice straw on aqueous solution quality and fastness quality of dyed fabric. The results showed that increasing the absorption time increased the percentage of color removal efficiency until it was stable at 80 min soaking time onward. The alkaline treated rice straw gave the highest percentage of the percentage of color removal efficiency. Determination on the fastness quality of dyed fabric; it was found that, non-treated, acidic treated and alkaline treated rice straw potentially removed the excessed color form the dyed fabric which the fastness quality of dyed fabric was improved.

Short-term changes in chemical and microbial characteristics of paddy soil in response to consecutive addition of organic ameliorants in a rice–rice–vegetable rotation system

ABSTRACT With regard of the problems of soil acidification and soil degradation caused by high intensive planting in south China, a 2-year pot experiment consisting of six harvests under a rice–rice–vegetable rotation cropping system was conducted to assess the effects of NPK+ rice straw (RS) and combined application of RS with peanut bran, biochar, and organic fertilizer on soil chemical and microbial characteristics in paddy soil. The control treatment received chemical fertilizer alone. Results showed that RS and the combination of RS with organic ameliorants, especially NPK+ rice straw + biochar (RSBC) treatment led to the greatest improvement of soil pH, soil organic carbon, microbial biomass carbon, and total nitrogen (TN) content, and urease (UE), acid phosphatase (ACP) and catalase (CAT) activities concurrently without yield sacrificing, which inferred that RSBC treatment could be an effective measure to alleviate soil acidification, boost carbon sequestration and nutrients content as well as soil enzyme activities in rice-rice-vegetable rotation system. Besides, Pearson’s correlation analysis showed that soil mineral nitrogen (Nmin) content was negatively related to pH, and the available potassium (AK) content was positively related to UE and CAT activity but negatively related to ACP activity. Canonical correspondence analysis demonstrated the Nmin and AK explained 27.2% and 13.7% of the variation in microbial species, respectively. Therefore, it is believed that soil Nmin and AK content could be the primary factors of soil microbial properties under the rice-rice-vegetable rotation system.

The Leaching of Iron and Loss of Phosphate in Acid Sulphate Soil Due to Rice Straw and Phosphate Fertilizer Application

Low phosphorus (P) availability and high iron (Fe) concentration are the dominant characteristics of acid sulphate soils (ASS). Optimum agricultural management practices are required to leach the excess Fe2+ and to prevent or minimize loss of P from the soil in order to obtain conditions favorable for rice growth. The aim of this experiment was to study the effect of organic matter (OM) application in the form of rice straw (RS) on leaching of Fe and loss of P in an acid sulphate soil. The experiment was conducted in the glasshouse consisting of three treatment factors utilizing the completely randomized design with three replications. The first factor was soil condition consisting of continuous application of RS and without RS during the past five years. The second factor was application of fresh RS consisting of fresh RS application and without fresh RS application, whereas the third factor was P application consisting of three rates of SP-36 fertilizer (0.5, 1.0 and 1.5 times of the recommended rate). The results showed that RS application was effective in preventing P loss from the soil at 6 weeks after planting (WAP) and decreased the pH of leachate at all observations time but it increased Fe2+ concentration in leachate (0.07-0.42% Fe2+ in the soil were leached or 2-5 folds higher than without RS application).

Application of Rice Straw Compost with Different Bioactivators on the Growth and Yield of Rice Plant

Turnover of organic matters to the soil can increase the efficiency of chemical fertilizers, improve the plant growth and sustain the environment. Field experiment was carried out in the Buyut Udik Village, Gunung Sugih District, Central Lampung from May to August 2009. Rice straw was composted by three kinds of decomposer (bioactivator A, B, and C). Rice straw compost (2 Mg ha-1) was applied to the paddy-field soil that was planted by rice (Oryza sativa) of Ciherang Variety. The experiment was arranged in a randomized block design with three replicates. The results showed that application of rice straw compost reduced the numbers of empty grain per tiller compared to control (without compost) in which control had the highest percentage of empty grain (15.9%). The application of rice straw compost that was decomposed by bioactivator A gave the highest numbers of grain per panicle and yield per plot as followed 162.5 seed and 33 kg plot-1, respectively. Application of various rice straw composts that were decomposed by three kinds of bioactivator increased the rice grain up to 13-26% compared to control.

Enhanced Soil Chemical Properties and Rice Yield in Acid Sulphate Soil by Application of Rice Straw

Swampland development such as acid sulphate soil for agricultural cultivation has various problem, including high soil acidity, fluctuated and unpredictable water flooding and the presence of toxic elements such as Fe which resulting in low crop yields. The research was conducted at the experimental station Belandean, Barito Kuala regency in dry season 2007. The objective of research was to study the effect of rice straw on the dynamic of soil pH, the concentration of iron and sulphate and yield on tidal land acid sulphate soil at two different water inlet channel. This research was designed in RCBD (Randomized Completely Block Design) with five treatments (0, 2.5, 5.0, 7.5 and 10 Mg ha-1) and four replications. Dolomite as much as 1 Mg ha-1 was also applied. This research was divided into two sub-units experiment i.e. two conditions of different water inlet channel. The first water channels were placed with limestone and the second inlet was planted with Eleocharis dulcis. The results showed that (i) rice straw application did not affect the dynamic of soil pH, concentration of iron and sulphate, and (ii) the highest yield was obtained with 7.5 Mg ha-1 of rice straw.

Rice straw serves as additional carbon source for rhizosphere microorganisms and reduces root exudate consumption

Straw application is a common agricultural fertilisation practice, providing an additional carbon and nutrient source for soil microorganisms. We investigated the influence of rice straw application on root exudate consuming microorganisms in the rhizosphere of Zea mays based on 13CO2 pulse labelling and phospholipid fatty acid stable isotope probing (PLFA-SIP) in a paddy soil under rice-maize crop rotation. The application of straw decreased the labelling of microbial PLFAs in the rhizosphere of 30 and 40 day old maize plants by 70% compared to treatments without straw. This decrease could partially be explained by a lower rate of CO2 assimilation of the plant in the presence of rice straw. In addition, the uptake of root exudates by rhizosphere organisms was decreased due to the presence of the rice straw, which serves as an additional carbon source for these microorganisms.

Effect of the long-term application of organic matter on soil carbon accumulation and GHG emissions from a rice paddy field in a cool-temperate region, Japan. -I. Comparison of rice straw and rice straw compost -

ABSTRACT The influence of the long-term combination of rice straw removal and rice straw compost application on methane (CH4) and nitrous oxide (N2O) emissions and soil carbon accumulation in rice paddy fields was clarified. In each of the initial and continuous application fields (3 and 39−51 years, respectively), three plots with different applications of organic matter were established, namely, rice straw application (RS), rice straw compost application (SC) and no application (NA) plots, and soil carbon storage (0−15 cm), rice grain yield and CH4 and N2O fluxes were measured for three years. The soil carbon sequestration rate by the organic matter application was higher in the SC plot than in the RS plot for both the initial and continuous application fields, and it was lower in the continuous application field than in the initial application field. The rice grain yield in the SC plot was significantly higher than those in the other plots in both the initial and continuous application fields. Cumulative CH4 emissions followed the order of the NA plot < the SC plot < the RS plot for both the initial and continuous application fields. The effect of the organic matter application on the N2O emissions was not clear. In both the initial and continuous application fields, the increase in CH4 emission by the rice straw application exceeded the soil carbon sequestration rate, and the change in the net greenhouse gas (GHG) balance calculated by the difference between them was a positive, indicating a net increase in the GHG emissions. However, the change in the GHG balance by the rice straw compost application showed negative (mitigating GHG emissions) for the initial application field, whereas it showed positive for the continuous application field. Although the mitigation effect on the GHG emissions by the combination of the rice straw removal and rice straw compost application was reduced by 21% after 39 years long-term application, it is suggested that the combination treatment is a sustainable management that can mitigate GHG emissions and improve crop productivity.

Effects of water and rice straw management practices on water savings and greenhouse gas emissions from a double-rice paddy field in the Central Plain of Thailand

Abstract Rice-rice (double-rice) cropping in the Central Plain region of Thailand relies heavily on irrigation water inputs for cultivation under flooded conditions, which is increasingly constrained by water scarcity. In this production system, farmers often burn or incorporate rice straw (RS) in the field. The effects of the combined use of water and RS management on irrigated lowland double-rice cropping, with respect to irrigation water savings, grain yields, and greenhouse gas (GHG) emissions, remain largely unknown. Field experiments of two consecutive rice-growing seasons in 2016–2017 were conducted at the Ayutthaya Rice Research Center in Ayutthaya, Thailand, to investigate the effects of different water and RS management practices on irrigation water savings, rice grain yields, and GHG emissions. The treatments consisted of two water regimes (continuous flooding [CF], alternate wetting and drying [AWD; 15 cm threshold water level below the soil surface for irrigation]) and three RS management practices (RS incorporation [RS-I], RS burning [RS-B], without RS incorporation and burning [WRS]). Parameters such as irrigation water inputs, soil characteristics (pH, temperature, water content), above-ground biomass, and grain yields were measured. The static vented flux chamber technique was used to measure GHG emissions (CH4 and N2O fluxes). AWD irrigation significantly reduced water inputs compared to CF in both growing seasons; however, there were more water savings in the dry season. AWD also resulted in higher grain yields compared to CF in both growing seasons. The average CH4 emissions from WRS plots were significantly lower compared to both RS-I and RS-B plots, regardless of the growing seasons. However, RS-I and RS-B plots under AWD had 39% and 63% lower CH4 emissions, respectively, in the wet season, while the corresponding values were 37% and 36%, respectively, in the dry season compared to the average CH4 emissions from these RS treatments under CF. Water and RS management did not significantly influence the average flux of N2O emissions from paddy fields in the wet season; however, CF had a lower average N2O flux than AWD in the dry season. The average flux of N2O emissions were very low compared to the CH4 emissions flux in both seasons. Averaged across two seasons, the yield-scaled global warming potential (GWP) under AWD was reduced by 34% compared to CF, and under WRS it was reduced by 36% and 29% compared to RS-I and RS-B, respectively. RS application, either as soil incorporation or open-field burning, had little or no effect on irrigation water savings and grain yields; however, the yield-scaled GWP was significantly higher from plots with RS-I or RS-B than WRS plots. Among the water regime and RS management practices tested, AWD irrigation without any RS application (soil incorporation or burning) can be employed for maintaining the yield-scaled GWP of irrigated lowland double-rice cropping at a low level.

Effects of biochar addition on enzyme activity and fertility in paddy soil after six years

A field experiment was conducted to examine the effects on soil fertility and enzyme activities in paddy field after six years of one-split rice straw-derived biochar [0 (BC0), 7.5(BC1), 15(BC2), 22.5(BC3) t·hm-2] and rice straw (3.75 t·hm-2, STR) application. The results showed that soil organic carbon, available phosphorus and rapidly available potassium concentrations significantly increased, by 34.6%, 12.4% and 26.2%, respectively. Soil pH and soil bulk density were significantly reduced, but total nitrogen content had no significant difference compared with BC0. Biochar addition significantly increased the activities of soil urease and acid phosphatase. The soil fluorescein diacetate (FDA hydrolase) and arylsulfatase activity were inhibited to varying degrees. Among them, BC2 treatment increased soil urease activity by 36.5%. The soil acid phosphatase activity increased with the increases of biochar application rate, which was positively correlated with soil available phosphorus concentration. FDA hydrolase and urease activity had positive correlation with soil available potassium content, while soil acid phosphatase and arylsulfatase activity had positive correlation with soil bulk density. After six years, soil dehydrogenase and polyphenol oxidase activity significantly increased by 48.8% and 27.5%, respectively, while catalase activity significantly decreased when compared with control BC0. STR treatment increased activities of soil urease, FDA hydrolase, dehydrogenase, acid phosphatase and arylsulfatase significantly, while decreased the catalase and polyphenol oxidase activities by 23.4% and 15.9%, respectively.

Does rice straw application reduce N2O emissions from surface flow constructed wetlands for swine wastewater treatment?

Rice straw was applied often as a carbon source to improve nitrogen removal; however, few studies have considered the effect of rice straw on nitrous oxide (N2O) emission during nitrogen removal in constructed wetlands (CWs). We constructed eighteen combined systems, consisting of rice straw ponds and surface flow CWs to investigate the effect of rice straw application on N2O emission in three strengths of swine wastewater treatments. The results showed rice straw (RS) treatment increased 131.5% of N2O emission factor from low strength CWs, but decreased 37.2-43.7% of N2O emission factors for medium and high strengths compared with no rice straw (NRS) treatment. The RS application led to an average 10.7% increase in the potential denitrification rate, and simultaneously enhanced gene abundances of the total bacteria (16S rRNA), ammonia-oxidising archaea, ammonia-oxidising bacteria, nitrate reductase, and N2O reductase (nosZ) for all strengths CWs. The multiple regression model revealed N2O emissions were strongly related to water temperature, nitrate, chemical oxygen demand, and denitrification genes. The proportion of nosZ gene abundance in 16S rRNA was higher in RS (0.7-1.3%) than NRS (0.4-0.9%) for medium and high strengths, while an opposite trend was observed for low strength. The discrepancy was responsible for increasing or decreasing N2O emission by RS application among different strengths. These findings indicated the effectiveness of RS application to control N2O emissions from the surface flow CWs was related to the pollution level of wastewater.

Water extractable organic carbon and nitrogen and their stable isotopes from long-term experiment in a Japanese rice paddy

Hot water- and water-extracted organic matter was extracted from soil samples collected after a 31-year long-term experiment which aimed to assess the effect of different fertilization strategies (inorganic fertilizers and organic matters) commonly used for paddy rice cultivation in Yamagata, northeastern Japan. The ratio of soil to extracted water was 2:3. The amounts of hot water-extracted organic carbon and nitrogen (HWEOC and HWEN) at 80 o C and 16 hours, water-extracted organic carbon and nitrogen (WEOC and WEN) at room temperature, and their δ 13 C and δ 15 N were measured from the five fertilizer treatment plots as [1) PK, 2) NPK, 3) NPK + 6 Mg ha -1 rice straw (RS), 4) NPK + 10 Mg ha -1 rice straw compost (CM1), and 5) NPK + 30 Mg ha -1 rice straw compost (CM3)], for surface (0-15 cm) and subsurface (15-25 cm) layers. HWEOC and WEOC accounted for an average of about 1.5 1 and 0.66% of SOC, while HWEN and WEN accounted for an average of about 1.09 and 0.40% of soil TN, respectively. About 90% of the extracted N was organic form among all treatments . The values of δ 13 C for HWEOC and WEOC ranged from -28.2 to -26. 5 ‰ and from -28.3 to -27.0‰, similar to the original rice straw and rice straw compost , and lower than the value of original soil at -22.5 ‰. The values of δ 15 N of HWEN, WEN and bulk soil ranged from 0. 8 to 3. 8 ‰, from 1.0 to 4.0‰, and from 0. 8 to 2. 8 ‰, respectively. It was clear that δ 15 N decreased in RS but increased in CM3 treatments. Our results indicated that the amounts of h ot water- and water-extracted organic matter were affected by long-term application of inorganic fertilizers and organic matter s remarkably. However, the values of δ 13 C for HWEOC and WEOC were not different among 5 treatments, but values of δ 15 N of HWEN and WEN were affected by RS and CM3 applications clearly .

Phytoextraction potential of soils highly polluted with cadmium using the cadmium/zinc hyperaccumulator Sedum plumbizincicola

A three-crop repeated phytoextraction experiment was conducted using four soils (S1–S4) highly polluted with cadmium (Cd) and two enhanced phytoextraction pot experiments using the most polluted soil (S4) to investigate the feasibility of Cd removal from highly polluted soils using the Cd/zinc (Zn)-hyperaccumulator Sedum plumbizincicola. Shoot biomass showed no significant difference during the repeated phytoextraction experiment on the four test soils and shoot Cd content showed a decreasing trend with the three consecutive crops in soils S1, S2, and S3 but not in soil S4. The Cd removal rates in soils S1, S2, S3, and S4 were 84.5, 81.6, 45.3, and 32.4%, respectively. Rice straw application increased Cd extraction efficiency by 42.6% but the addition of ethylenediaminedisuccinic acid, biochar or nitrogen had no effect on Cd remediation. Shoot Cd content increased significantly (1.57 and 1.71 times, respectively) at low (S0-1) and high (S0-2) sulfur addition rates. Soil extractable-Cd in S0-1 after the experiment showed no significant difference from the control but was 2.43 times higher in S0-2 than in the control. These results indicate that S. plumbizincicola shows good prospects for the phytoextraction of Cd from highly polluted soils and that the process can be enhanced by adding straw and/or sulfur to the soil.

Response of rice grown in saline soil as influenced by the application of agricultural amendments and moisture regimes

The experiment was carried out with rice (BRRI dhan48) grown in saline soil at the premises of the Department of Soil, Water and Environment, University of Dhaka to evaluate the impacts of agricultural amendments, such as rice hull (RH), rice straw (RS) and sawdust (SD) each applied at the rates of 0, 4 and 8 t ha-1 in moist (80% moisture) and saturated soil conditions. Most of the growth and yield components of rice were found to increase significantly (p ≤0.05) with the increased rates regardless of kinds of organic treatments under both the moisture levels. The tallest plant heights (99 cm in moist, 105 cm in saturated condition) were recorded at maturity stage of rice with the RH8RS8SD8treatment, which received the highest rates of these three organic amendments. The shortest plant heights (79 cm in moist; 86 cm in saturated conditions) were recorded in control pot (RH0RS0SD0), where no amendment was made. The maximum numbers of tillers were observed in RH8RS8SD8followed by RH8RS8SD4, RH8RS4SD8, RH4RS8SD8 and RH4RS4SD8 treatments at saturated condition. The straw dry matter and grain yields of rice were also found to vary significantly (p ≤0.05) by the individual application of rice hull, rice straw, sawdust and moisture conditions, but their combined effects were found to be highly significant at their higher doses of combination. The highest grain yield (4.4 t ha-1) was recorded in RH8RS8SD8 treatment followed by RH8RS8SD4 (4.2t ha-1) and RH8RS4SD8 (4.1t ha-1) at saturated condition. Harvest index and 1000 grain weight of the rice were attained positive under both the moisture conditions, but at saturated condition of the soil, the amendments (RH, RS and SD) produced better response for these components compared to those of the moist soil condition.&#x0D; J. Biodivers. Conserv. Bioresour. Manag. 2018, 4(2): 33-42

Organic amendments of soil and its effect on the NPK contents in rice plants grown on saline soil

The potential and effectiveness of the indigenous organic amendments such as rice hull (RH), rice straw (RS) and sawdust (SD) at the rates of 0, 2 and 4 t ha-1, respectively on N, P and K contents of BRRI Dhan-47 grown on saline soil under variable moisture (field moist: FM and 2-5 cm standing water: SW) levels were evaluated in the field experiment. The N, P and K contents in the shoot at maturity stage of rice increased significantly (p&lt;0.05) by the individual and the combined application of these amendments. The maximum contents of N (26.7 g kg-1: FM and 25.7 g kg-1: SW) were attained by the T27 (RH4SD4RS4) followed by the T26 (RH4SD4RS2) treatments. Among the three types of amendments regardless of their doses, the application of RS exerted best response (16.75 g N kg-1) followed by SD (16.35 g N kg-1) and RH (16.04 g N kg-1) in increasing N content of rice plants at field moist condition of the soil. The maximum P contents (2.49 g kg-1: FM and 2.67 g kg-1: SW) were recorded by the T27 (RH4SD4RS4) followed by the T26 (RH4SD4RS2) treatments and the lowest contents of P (0.40 g kg-1: FM and 0.42 g kg-1: SW) were obtained from the control plots. The content of P in rice shoots was slightly higher in SW than that of FM conditions. The maximum contents of K (18.2 g kg-1 in FM and 15.8 g kg-1 in SW) were obtained by the application of RH4SD4RS4 (T27) followed by the RH4SD4RS2 (T26) and the lowest contents of K (2.8 g kg-1: FM; 2.7 g kg-1: SW) were determined in the control plots. The contents of N and K in rice shoots were slightly higher in the FM than those of the SW conditions regardless of these amendments.Bangladesh J. Sci. Ind. Res.53(4), 297-304, 2018

Black carbon yields highest nutrient and lowest arsenic release when using rice residuals in paddy soils

Rice straw increasingly remains on the fields for nutrient supply to the next generation of crop plants. It can be applied either fresh or after burning to black carbon or ash. A central concern during rice cultivation is accumulation of carcinogenic arsenic and the question arises how much rice straw application contributes to nutrient versus arsenic supply in paddy fields. Laboratory incubation experiments were performed to assess the effect of rice straw, black carbon and ash on element mobilization. Our experiments showed initially higher silicon and phosphorus release from black carbon compared to fresh straw amendments. However, more re-sorption to soil lead to finally slightly lower pore water concentrations for black carbon versus fresh straw amendments. Highest arsenic, iron, manganese and dissolved organic carbon concentrations were observed after fresh rice straw application. Black carbon and ash application lead to only minor increases of arsenic compared to controls without amendments. Overall, for silicon and phosphorus the soil acts as sink while for iron and arsenic it was the main source. In summary, burning of rice straw to black carbon prior to application seems to yield a high increase in desired nutrient and a decrease in undesired arsenic mobilization in paddy soils.

Integration of Allelopathic Crop Residues and NPK Fertilizer to Mitigate Residue-Phytotoxicity, Improve Soil Fertility and Wheat Growth under Different Moisture Conditions

ABSTRACT: Phytotoxic effects of allelopathic crop residues are important to trickle for their use as a source of organic amendments to improve soil fertility. In present study, through pots and two year field studies, we examined the integrated effect of allelopathic residues and NPK fertilizer treatments including T0 (control), T1 (200-150-100 kg NPK ha 1), T2 (100-75-50 kg NPK ha-1 + mung bean straw 4 t ha-1), T3 (100-75-50 kg NPK ha-1 + rice straw 4 t ha-1), T4 (mung bean straw 8 t ha-1) and T5 (rice straw 8 t ha-1) under different water regimes on soil fertility and wheat crop. Solo application of mung bean residue and rice straw caused significant inhibition of various germination and growth traits of wheat while minimal inhibition occurred when allelopathic straws were integrated with NPK fertilizer both under laboratory and field conditions, especially under 14 days of alternate wet/dry cycles. Among fertilizer treatments, mung bean residue caused a greater increase in soil organic carbon, available nitrogen and available phosphorus, while there was maximum percent increase in available potassium with T1 (200-150-100 kg NPK ha-1). Maximum increase in grain yield (30% and 33%) was achieved with T2 (100-75-50 kg NPK ha-1 + mung bean straw 4 t ha-1) during 2014-15 and 2015-16, respectively. Integration of allelopathic crop residues with inorganic fertilizers and alternate wet/dry cycles can help to reduce the possible phytotoxic effect of allelopathic residues for sustainable wheat production.

Effect of rice straw application on water quality and microalgal flora in fish ponds

The present experiment was conducted to assess the effects of decomposing rice straw on algal flora as well as physical, chemical, and biological-parameters of 9 earthen fish ponds of 2100m3 for each with one-meter average depth. It was conducted for 6 months using three treatments. Each pond was stocked with 6000 fish fries of Nile tilapia (Oreochromis niloticus). Results showed that water quality decreased with increased loading rates of rice straw. Most of water quality parameters including EC, TDS, total alkalinity, total phosphorus, NO3, NO2, chlorophyll a, and pH were significantly lower in rice straw treatments than control. Total ammonia, Secchi disc visibility and orthophosphate were significantly higher with increase rice straw loading than control. Cyanophyceae constituted the dominant algal group at the initial phase at all examined ponds. This dominance remained stable in control ponds by the end of experiment. In contrast, in the final stage of the experiment Chlorophyceae and Bacillariophyceae dominate in T2 and T3 treatments compared with control. The results of this work illustrated that the decrease of algal count was related to action of allelochemicals discharged from rice straw aqueous extract leading to suppress growth of some algal species. Hence, this technique is a way to reduce the cost and reduce the use of herbicides, by providing natural compounds that can be obtained from agricultural waste.

Effect of water and rice straw management practices on yield and water productivity of irrigated lowland rice in the Central Plain of Thailand

Rice cultivation techniques with less irrigation water input are crucial for global food security in the context of changing climate scenarios. Alternate wetting and drying (AWD) is among such water-saving techniques, which could potentially reduce irrigation water input for rice cultivation through alteration of soil submergence period with period of soil non-submergence (unsaturated soil conditions) during the growing season. Rice straw is often scattered in the field after harvest or burned in intensive rice cultivation systems. Response of irrigated lowland rice with respect to grain yield and water use under different water and rice straw management practices largely remains unknown. Field experiments were conducted at the Ayutthaya Rice Research Center, Ayutthaya, Thailand, in two consecutive rice-growing seasons (wet and dry) of 2016–2017 to evaluate the growth, yield and water productivity of irrigated lowland rice under different water and rice straw management practices. The treatments included were two water (continuous flooding [CF] and AWD) and three rice straw management practices (rice straw incorporation [RS-I], rice straw burning [RS-B] and without rice straw incorporation and burning [WRS-I + B]). AWD increased grain yield by 15% in the wet season and by 7% in the dry season compared with CF. Other yield components such as panicle number m–2, spikelet number panicle–1 and 1000-grain weight were also higher under AWD compared with CF depending on the growing season. AWD reduced total water input by 19% in the wet season and by 39% in the dry season resulting in an improvement in total water productivity by 46% in the wet season and by 77% in the dry season relative to CF. Rice straw application either as soil incorporation or open-field burning had no effect on grain yield, water-saving potential and water productivity of the tested variety regardless of the growing season. Although its positive role in supplying plant nutrients and maintaining soil fertility, rice straw incorporation in the field or burning should be discouraged due to negative environmental impacts. AWD (15 cm threshold water level below the soil surface for irrigation or with soil water potential of ≥ −20 kPa [AWD15]) is recommended for irrigated lowland rice cultivation from a point of view of reducing total water input without jeopardizing yield.