Impact of sewage water irrigation on agricultural soil

The rapidly increasing population growth and the steady increase in water requirements for agricultural and industrial development have placed severe stress on the water resources available and the long term use of sewage water for irrigation highly affects soil properties. In this study soil samples were collected from a cauliflower field prior and after sewage water irrigation, and the impact of sewage water irrigation on physical, chemical, and biological properties of soil was compared. For this, tested were pH, Electrical Conductivity (EC), Organic Carbon, available Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Zinc, Iron, Copper, Manganese, and microbial activity. Soil microbial biomass carbon, basal soil respiration, total viable count of bacteria, coliform population, Pseudomonas species, and Azotobacter significantly increased after sewage water irrigation as compared to prior to irrigation. Nevertheless, the bulk density and Rhizobium species of the soil flooded with sewage water was decreased relative to the same characteristics prior to irrigation. Cauliflower yield was significantly increased when sewage water flooded field as compared to the tube well water flooded field (i.e., water delivered via an iron pipe). Escherichia coli contamination was greater in sewage water and groundwater that can pose health risks for the nearby communities, to farmers and consumer of farm products. Hence, the efficient use of sewage and municipal wastewater successfully increase water resource for irrigation and may help in expanding agricultural production. But excessive use of sewage water may also affect the soil flora and fertility.

TRACE ELEMENTS DISTRIBUTION IN HEIRLOOM PADDY PANDASAN CULTIVATED UNDER FIELD CONDITIONS OF DRY AND WET SOIL

Trace elements phytoavailability depends on the physical and chemical propertiesof soil. At the Crocker range of West Coast Sabah, Malaysia, the Pandasan paddyvariety can be cultivated as flooded rice paddies or upland rice on acidic soil.Pandasan paddy samples were collected in Kiulu subdistrict from traditionalfarmer at two different locations. Available sources of trace elements were fromweathering, fertilizers and pesticides. Soil and plant samples were collected aftertwo months of seed sowing and during harvest season which was five months oldfor heavy metal analysis by inductively coupled plasma optical emissionspectrometry (ICP-OES). Translocation factor of arsenic from root to grainindicated this trace element was very mobile in Pandasan paddy cultivated at drysoil compared to wet soil followed by zinc. Although, cadmium was not detected inpaddy cultivated at flooded field for both, soil and plant, cadmium was detected insoil and plant roots cultivated in dry condition. Enrichment factor results suggestedthat Pandasan plant cultivated on dry soil was only a good bioindicator for leadand zinc. Pandasan grain was rich with iron followed by zinc. Selected heavymetals accumulation in Pandasan grain cultivated in flooded field did not exceededthe permissible limit of Malaysia Food Regulation 1985. However arsenic andplumbum concentration in Pandasan grain harvested from dry soil exceeded thepermissible limit of Malaysia Food Regulation 1985. Health risk of heavy metalstoxicity can be reduced if Pandasan paddy is cultivated in flooded field comparedto dry soil.

Benzobicyclon Activity on Common Louisiana Rice Weeds

A study was conducted at three locations in Louisiana to evaluate the response of common Louisiana rice weed species to different rates of application of benzobicyclon herbicide. Benzobicyclon was applied at 31, 62, 123, 185, 246, 493, 739, 986, and 1,232 g ai ha–1into flooded field conditions when ducksalad was at the first elongated-leaf stage. Barnyardgrass, false pimpernel, and yellow nutsedge control never exceeded 50% from any rate of benzobicyclon applied, averaged across evaluation timing. Ducksalad control, averaged across evaluation timing, was 83% when treated with 493 g ha−1and did not increase when treated with higher rates of benzobicyclon. At 42 d after treatment (DAT), purple ammannia and Indian toothcup treated with 185 and 246 g ha–1of benzobicyclon were controlled 58% and 81%, respectively, and did not differ in control compared with higher rates of benzobicyclon. All weeds were hand-harvested from each plot and separated by species at the conclusion of the study. No differences in fresh-weight biomass were observed for barnyardgrass, false pimpernel, purple ammannia, or yellow nutsedge. Treatment with benzobicyclon at ≥62 g ha–1resulted in reduced ducksalad fresh weight 42 DAT compared with the nontreated sample. Indian toothcup fresh weight was reduced 77% to 96% compared with the nontreated sample when treated with benzobicyclon at 246 to 1,232 g ha–1.