Effects of Drainage on Greenhouse Gas Emissions and Yields of Lowland Rice-Wheat Rotation System in East China

The subtropical region of East China is characterized by abundant water and temperature resources conducive to crop cultivation, and large areas of lowland have been widely used for agricultural planting. To explore the feasible methods of greenhouse gases (GHGs) reduction for rice-wheat rotation system, shallow ditch (SD) and deep ditch (DD) treatments in the wheat season were set up for drainage to control the water content in soil, with the conventional non-ditching treatment as the control group (CG). Results showed that methane (CH4) emissions from paddy soil were in the majority in global warming potential (GWP) in rice-wheat rotation system. In the three years, compared with that of CG, the CH4 cumulative emissions of SD and DD were reduced by 65.80% and 63.42% (rice season), and 101.37% and 77.28% (wheat season), respectively; the nitrous oxide (N2O) cumulative emissions of SD and DD were reduced by 27.62% and 11.30% (rice season), and 1.53% and -37.40% (wheat season), respectively; the total GWP produced by SD and DD in the three years was reduced by 58.78% and 52.22%, respectively; GHG emission intensity (GHGI) of SD and DD declined by 60.67% and 53.85%, respectively; the CH4 emission flux was significantly positively correlated with atmospheric temperature and 5 cm ground temperature, but negatively correlated with soil Eh; when the soil Eh value was lower than -150 mV, the CH4 emission flux increased significantly, indicating that -150 mV was the key soil Eh value for CH4 emissions in this area; in addition, both SD and DD led to markedly decrease in soil organic matter content and an increase in soil pH. The findings indicate that SD and DD not only ensure stably increasing production, but also effectively reduce GHG emissions.

Identification of climate induced optimal rice yield and vulnerable districts rankings of the Punjab, Pakistan

The study attracted to insinuate the inhabitant anomalies of the crop yield in the districts of the Punjab where climate variation, inputs utilization, and district exponents are indispensable factors. Impact evaluation of sowing and harvesting dates for rice yield has been analyzed. Suitable sowing and harvesting dates and potential districts for the crop are proposed. Data consisting of 13,617 observations of more than 90 factors encompassing valuable dimensions of the growth of the crops collected through comprehensive surveys conducted by the Agriculture Department of Punjab are formulated to incorporate in this study. The results establish the significant negative repercussions of climate variability while the impacts vary in the districts. The crop yield deteriorates considerably by delaying the sowing and harvesting times. Districts climate-induced vulnerability ranking revealed Layyah, Jhelum, Mianwali, Khanewal and Chinniot, the most vulnerable while Kasur, Gujrat, Mandi Bhauddin, Nankana Sahib and Hafizabad, the least vulnerable districts. Spatial mapping explains the geographical pattern of vulnerabilities and yield/monetary losses. The study ranks districts using climate-induced yield and monetary loss (222.30 thousand metric tons of rice which are equal to 27.79 billion PKR climatic losses in single rice season) and recommends: the formation of district policy to abate the adverse climate impact, utilization of suitable climate variation by adhering proper sowing and harvesting times, setting the prioritized districts facing climate-induced losses for urgent attention and preferable districts for rice crop.

Gross Ecosystem Productivity Dominates the Control of Ecosystem Methane Flux in Rice Paddies

Although rice paddy fields are one of the world’s largest anthropogenic sources of methane CH4, the budget of ecosystem CH4 and its’ controls in rice paddies remain unclear. Here, we analyze seasonal dynamics of direct ecosystem-scale measurements of CH4 flux in a rice-wheat rotation agroecosystem over 3 consecutive years. Results showed that the averaged CO2 uptakes and CH4 emissions in rice seasons were 2.2 and 20.9 folds of the wheat seasons, respectively. In sum, the wheat-rice rotation agroecosystem acted as a large net C sink (averaged 460.79 g C m−2) and a GHG (averaged 174.38 g CO2eq m−2) source except for a GHG sink in one year (2016) with a very high rice seeding density. While the linear correlation between daily CH4 fluxes and gross ecosystem productivity (GEP) was not significant for the whole rice season, daily CH4 fluxes were significantly correlated to daily GEP both before (R2: 0.52–0.83) and after the mid-season drainage (R2: 0.71–0.79). Furthermore, the F partial test showed that GEP was much greater than that of any other variable including soil temperature for the rice season in each year. Meanwhile, the parameters of the best-fit functions between daily CH4 fluxes and GEP shifted between rice growth stages. This study highlights that GEP is a good predictor of daily CH4 fluxes in rice paddies.

Performance of Two Rice (Oryza sativa L.) Genotypes Under Modern and Conventional Farming Methods in Three Locations in Iraq

The conservation of natural resources like soil and water and reduces chemical pollution in the environment is the desired goal of the directions of improving the performance of important crops for meeting the global food demand. However,System of Rice Intensification (SRI), is a rice cropping system that is consistent with Conservation Agricultural (CA) and Sustainable Agriculture (SA). The current study was aimed to investigate the effects of SRI method on grain yield and its components in two rice varieties compared with conventional practice in farmers' fields (CFM) in different environmental conditions in Iraq. The study was conducted in the fields during the rice season 2019 in three provinces in the south of Iraq (Najaf, Diwaniya and Muthanna). Anber33 and Jasmine rice varieties were grown in each location and the traits were conducted at sites having 2 donum of land (5,000 m2).The trial was performed as a factorial experiment based on a randomized complete blocks design (RCBD) having three blocks. The results showed superior significant of SRI method compared to CFM method in traits (plant height and panicle length, number per panicle, and percentage of unfilled grains). Furthermore, SRI method gave higher grain yield as a percentage with both varieties in each province (25.6% in Muthanna, 24.5% in Najaf, and 13.2% in Diwaniya province) compared to CFM. However, grain yield in Jasmine variety was higher than on Anber33 approximately 50% in three locations in this study. Overall, our results suggest that SRI method is the most convenient method in Iraq conditions due to the increased grain yield in rice compared to the CFM method.

Performance of Two Rice (Oryza Sativa L.) Genotypes Under SRI and Conventional Farming Methods in Three Locations in Iraq

The conservation of natural resources like soil and water and reduces chemical pollution in the environment is the desired goal of the directions of improving the performance of important crops that to meet the global food demand. However System of Rice Intensification (SRI), is a rice cropping system that is consistent with Conservation Agricultural (CA) and Sustainable Agriculture (SA). The current study was aimed to investigate the effects of SRI method on grain yield and its components in two rice varieties compared with conventional practice in farmers' fields (CFM) in different environmental conditions in Iraq. Study was conducted in the fields during the rice season 2019 in three provinces in south of Iraq (Najaf, Diwaniya and Muthanna ). Anber33 and Jasmine rice varieties were grown in each location and the traits were conducted at sites having two donum of land (5,000 m2). The trial was performed as factorial expriments based on a randomized complete blocks design (RCBD) having three blocks. The results showed superior significant of SRI method compared to CFM method in traits (plant height and panicle length, number per panicle and percentage of unfilled grains). Furthermore, SRI method gave higher grain yield as percentage with both varieties in each province (25.6% in at Muthanna, 24.5% in Najaf and 13.2% in Diwaniya province) compared to CFM. However, grain yield in Jasmine variety was higher than on Anber33 approximately 50% in three locations in this study. Overall, our results suggest that SRI method is the most convenient method in Iraq conditions due to the increased grain yield in rice compared to the CFM method.

Climate-Induced Perspective Variations in Irrigation Schedules and Design Water Requirements for the Rice–Wheat System

Conceptualizing the implications of climate change for crop evapotranspiration (ETc) and subsequent net irrigation water requirement (NIWR) is critical to sustaining Pakistan’s agriculture and food security. In this article, future ETc, NIWR, and design water requirements (DWR) were projected for the rice–wheat system of Punjab, Pakistan. Consistently increasing temperatures signify an impending hotter transition in the future thermal regime, accompanied by a substantial increase in monsoon rainfall. Future climate warming accelerated ETc and NIWR, which were compensated by 2–5 and 1–2 additional irrigations during the rice and wheat seasons, respectively. Future rice and wheat required 13–18 and 2–5 irrigations per season, respectively. Effective rainfall increments did not compensate for the warming-driven higher ETc and NIWR because of uneven and erratic rainfall distribution. Rainfall occurrence and the duration of peak irrigation demand were mismatched, resulting in surplus rainwater availability during the future rice season. The results suggest that DWR for 5- and 10-year return period droughts during the baseline period (965 and 1000 mm, respectively) should be revised to accommodate the additional 100–200 mm of irrigation water per season; otherwise, the study area will face an acute water shortage in the future.

Rice-Rape Rotation Benefits to Improve Radiation and Heat Use Efficiencies and Mitigate Global Warming Potential of Paddy Cropping Systems in Central China

Replacing bare fallow by rotation with winter cereal crops such as winter wheat and oil rape have been used to improve annual productivity in paddy cropping system in central China. However, the effects of rotation on light and heat resources utilization and greenhouse gases have yet to be measured. A two-year field experiment was conducted to compare solar radiation and heat use efficiencies, methane (CH4) and nitrous oxide (N2O) emissions and global warming potential (GWP) of two winter rotations: rice-wheat and rice-rape taking rice-fallow as a check. The results of this study showed that rice-wheat had the highest annual grain yield (two-year means were 16.2 t ha-1) and annual above ground biomass (32.9 t ha-1) followed by ricerape and by rice-fallow. No significant effect was observed for winter rotation on the performance of rice grain yield and growth, in spite of a large quantity of straw returning by winter crops. Solar radiation and heat resources utilization and their production efficiency were improved in the winter season by rotation with winter crops. Rice-wheat and rice-rape also increased light and heat resources utilization efficiency from the annual perspective. Compared with rice-fallow, CH4 flux in the rice season among the two studying years was increased by 42.0% by rice-wheat but was decreased by 35.6% by rice-rape. For the annual level, CH4 flux was promoted by 40.9% by rice-wheat and declined by 35.5% by rice-rape. For the rice season the N2O seasonal flux was increased by 54.2 and by 8.3% in rice-wheat and rice-rape plots, respectively. The values for GWP and for yield-scaled GWP were highest in rice-wheat and lowest in rice-rape system. In conclusion, rice-rape system could be a better choice to increase solar radiation and heat resources utilization and mitigate greenhouse gases emission. © 2021 Friends Science Publishers

Reasonable Nitrogen Fertilizer Management Improves Rice Yield and Quality under a Rapeseed/Wheat–Rice Rotation System

To determine the influence of N fertilizer management on rice yield and rice quality under diversified rotations and establish a high-yield, high-quality, and environmentally friendly diversified planting technology, a rapeseed/wheat–rice rotation system for 2 successive years was implemented. In those rotation systems, a conventional N rate (Nc; 180 kg/hm2 N in rape season, 150 kg/hm2 N in wheat season) and a reduced N rate (Nr; 150 kg/hm2 N in rape season, 120 kg/hm2 N in wheat season) were applied. Based on an application rate of 150 kg/hm2 N in the rice season, three N management models were applied, in which the application ratio of base:tiller:panicle fertilizer was 20%:20%:60% in treatment M1, 30%:30%:40% in treatment M2, and 40%:40%:20% in treatment M3. Zero N was used as the control (M0). The results showed that, under Nc and Nr in the rape season, M3 management produced an increase in rice yield. The average rice yields in 2018 and 2019 were 9.41 t/hm2 and 9.54 t/hm2, respectively. An increase in rice peak viscosity, hot viscosity, break disintegration, and chalkiness was achieved. Under Nc and Nr in the wheat season, the panicle fertilizer of 40%:40%:20% in rice season produced a higher rice yield. The average yield was 9.45 t/hm2 and 9.19 t/hm2, respectively, and an increase in rice peak viscosity, hot viscosity, and break disintegration was produced. Reduced N for rapeseed and the panicle fertilizer of 40%:40%:20% in rice season under a rapeseed–rice rotation system can be recommended to stabilize yield and ensure high-quality rice production and environmentally friendly rapeseed–rice rotation systems in southern China.

Effect of Ploughing Techniques on Water Use and Yield of Rice in Maugo Small-Holder Irrigation Scheme, Kenya

The objective of this study was to determine the effect of paddy rice ploughing techniques on water use and the yield of rice crop, as well as water use efficiency for rice growing in small-holder irrigation schemes. The study was conducted at a farmer’s field in Powo B sub-block of Maugo Irrigation Scheme. The period of study was from July 2019 to January 2020, which is the rice season. The experimental site was located in the vicinity of Olare Shopping Centre, Kamenya Sub-location, Kochia East Location, Kochia Ward, Rangwe Sub-County, Homa Bay County, Nyanza Region, Kenya in Maugo rice scheme in Kenya. In the study, four irrigation tillage practices were applied: ox-plough, conventional ox-plough, hand hoe and tractor ploughing. The results showed that conventional ox-ploughing consumed the highest amount of water at 1240 mm. The highest water use efficiency of 0.49 kg/m3 and highest yield of 5.7 tons/ha were observed for hand hoe ploughing. Use of the hand hoe ploughing technique increased yields by 20 percent, as compared to the conventional ox-ploughing. Therefore, the use of water for ploughing is not necessary in the study area. Future research will be needed to see how farmers are adopting the technology before scaling up to full mechanization, as partial mechanization was not profitable.