Assessment of water conservation technique in rice culture to develop water use policies

The rapid growth of world population has resulted in significantly increased global water demand. According to a recent report on limited water supply, conservation techniques and water use policies are needed to preserve water resources. Worldwide agriculture is the largest consumer of water, particularly for growing rice. Water use for rice production was chosen because rice will continue to be a staple crop for the majority of the world’s population and because of its pervasive use of water. Hence, this thesis was designed to investigate water conservation possibilities for rice production in two water management regimes: alternate flooding and drying, and continuous flooding (the latter is the traditional water management technique in irrigated rice culture). The alternate flooding and drying treatment reduced water use by 13-29 percent and increased rice grain yield by 33-36 percent. Results demonstrate that there is great potential to increase water use efficiency in wetland rice culture without reducing rice grain yield. Moreover, the results can be used to strengthen government water use policies in irrigated rice farming systems

Effect of plant residue and water management practices on soil redox chemistry, methane emission, and rice productivity

Approximately 5 % of rice growing area in Louisiana experience poor seedling or stand development attributed to anaerobic decomposition of excess plant residue, which create strongly reducing or toxic soil conditions. This study investigated plant residue and flooding regime effects on soil properties as related to rice growth and seedling development. Field experiments were conducted at several commercial farms in Southwest Louisiana (which have experienced problem with rice stand development) to relate observed restricted rice growth to soil redox chemistry and other chemical and physical properties. Field experiments were also conducted at the Crowley Rice Research Station in which various rates of rice straw amendment were added to replicate field plots to determine effect on rice growth and methane emission. The study also include greenhouse experiments on plant residue effect on soil chemical properties as related to rice seedling development and growth including effect of plant residues sources (rice straw or alligator weed on rice seedling germination). These studies showed source and quantity of plant residue significantly affected rice seedling development and germination rates of various commercial rice varieties. Alternating flooded and drained cycles significantly increased growth and grain yield of rice as compared with continuous flooded treatments containing high level of soil plant residue. High rates of plant residue addition increased methane emission (7,350 kg/ha/season) as compared with treatment receiving no added plant residue (370 kg/ha/season). Alternating flooded and drained cycles as compared with continuously flooded resulted in a 50 % reduction in methane emission and increased grain yield by 30 % in treatment receiving 24 t/ha plant residue added. Alligator weed plant residue source had greater effect on rice seedling development as compared with rice straw. Adoption of alternately flooded and drained water management practice, which improves soil chemical properties, can substantially increase rice growth and yield as well as reduces atmosphere methane emission from Louisiana rice soils

Adsorption and desorption of arsenate in Louisiana rice soils

Gedik, Kenan/0000-0001-8244-6935WOS: 000372082000010Adsorption and desorption of arsenic (As) in the soil are dominant parameters that affect the mobility and bioavailability of arsenic. Batch arsenate adsorption and desorption experiments were conducted using soils collected from three Louisiana, USA, aquaculture ponds representing different crayfish farming and rice cultural practices. Arsenate adsorption behavior in the soils was investigated using Freundlich and Langmuir sorption equations. Results demonstrated that the Langmuir isotherm model was the best fit based on statistical correlation with soil properties governing adsorption, for the entire range of arsenate concentrations for all soils. Adsorption of As(V) was governed by soil physicochemical properties especially Fe and Al oxides, clay and organic matter. Desorption of As(V) was initially fast, but with increasing incubation times desorption occurred progressively slower. Chemical fractionation of arsenic in the soils showed that the most mobile fraction represented 4.74-5.18% of the total arsenic. A part of this mobile fraction could potentially be taken up by rice and enter the food chain, but would require additional research to quantify

Distribution of arsenic and other metals in crayfish tissues (Procambarus clarkii) under different production practices

Gedik, Kenan/0000-0001-8244-6935WOS: 000389090100033PubMed: 27639469Louisiana is one of the world's largest producer of crayfish. Arsenic (As) and other metals (Cd, Cu, Pb and Zn) concentrations were determined in crayfish tissues, plant and soil samples collected from Louisiana paddy rice fields, where crayfish/rice rotation farming is a common practice. the samples were collected from November 2013 to April 2014 from three different crayfish farming systems. Concentration of As in rice grain, rice straw, and native vegetation ranged between 033 and 0.41, 3.14-4.93, and 326-5.89 mg kg(-1), respectively. the highest As levels in the crayfish external and internal body parts were found in gill (4.04 +/- 1.70 mg kg(-1)), followed by hepatopancreas (3.42 +/- 1.57 mg kg(-1)), exoskeleton (1.52 0.85 mg kg(-1)), and muscle (1.50 +/- 0.69 mg kg(-1)). Positive correlations between As levels in the crayfish muscle and the plant tissue on which they feed were found in all farming systems (r = 0.405-0.438). the biomagnification factor (BMF) of As in different tissues varied between 0.29 and 1.08, having gill and hepatopancreas were the highest As accumulation while the lowest biomagnification was observed in crayfish muscle tissues which is a food source for human. the As levels along with other metals in crayfish muscle tissue were in acceptable levels for human consumption under all crayfish/rice rotation practices. Further studies are needed in determining the percentage of organic and inorganic arsenic in crayfish tissue. Published by Elsevier B.V.Council of Higher Education of TurkeyMinistry of National Education - TurkeyWe would like to thank the Council of Higher Education of Turkey for supporting Kenan Gedik. We also thank William (Ray) McClain for suggestions and comments on the manuscript

Decreasing methane emission of rice by better crop management

A field experiment was conducted to determine the effect of water management techniques for maintaining rice production and reducing methane emission in a Crowley silt loam paddy soil receiving high rice straw additions. A 2 × 5 factorial experiment was arranged in a split-plot design with two water management practices; alternately flooded and drained and continuously flooded, and five rates of rice straw incorporation as subplot treatments (0, 3, 6, 12 and 24 t ha–1), with four replications. Rice yield was significantly greater in the alternately flooded and drained treatment as compared with the continuously flooded treatment. High rice straw application (12 and 24 t ha–1) reduced rice yield in both water management treatments. Methane emission increased with increase in the rice straw application rate. However, emissions were lower in the alternately flooded and drained treatment plots. The results demonstrate that draining a field for a short period of time during the growing season can enhance rice growth and rice yield while reducing methane emission