Weed Management in Rice-Wheat Cropping System through Remote Sensing： A Review

The productivity of the flee-wheat rotation of the Indo-Gangetie Plains is critical to India＇s food security. Severe weed competition resulting from the change in morphological characteristics of the modem high yielding varieties （HYV） led to intensive use of herbicides for weed control. Continuous and indiscriminate use of herbicides led to pollution as well as build up of resistant biotypes. This necessitates the need based use of herbicides. Identification of predominant weeds in rice-wheat cropping system through remote sensing and Geographic Information System （GIS） would help in reducing the load of herbicide on agro-eco system by reducing spray volume, application time and non-target spraying. This will help in developing site-specific weed management technique by geating only those areas with herbicide where weed densities exceed the economic threshold and may reduce application rate of herbicides in patches where weed densities are low. This paper reviews the literature on role of remote sensing for weed management not just to review their empirical findings, but to evaluate the role they have played and have the potential to play-in actual for weed management in flee-wheat cropping system （food bowl of India）.

Mechanical properties of straw basalt fiber reinforced concrete composites

One of the biggest problems responsible of the nonrenewable resources depletion and environmental issues is the construction industries,which generates large amounts of mineral waste and harmful emitted gases.Therefore,these problems generated the necessity to search for alternative natural building materials based on renewable resources.To study the mechanical characteristics and microstructural behavior of the concrete reinforced by raw wheat straw basalt fiber composite(RWSBFc),and treated rice straw basalt fiber composite(TRSBFc),a number of experimental tests were carried out with different composites ratios.Concrete compressive strength,splitting tensile strength,and flexural strength tests were considered as main parameters.The results showed that the RWSBFC has a positive effect on concrete flexural strength by increasing of 12.58%,compared with control samples.Also,it showed good enhancement in concrete flexibility and ductility.In contrast,both RWSBFc and TRSBFc showed uneven deterioration in concrete compressive strength and splitting tensile strength.To avoid the deterioration in compressive strengths of the various composites types,some improvement methods such as processors for the used straw,and adding some additives were recommended.

Phosphorus status and microbial community of paddy soil with the growth of annual ryegrass (Lolium multiflorum Lam.) under different phosphorus fertilizer treatments

Annual ryegrass （Lolium multiflorum Lam.） was grown in paddy soil in pots under different phosphorus （P） fertilizer treatments to investigate changes of P fractions and microbial community of the soil. The treatments included Kunyang phosphate rock （KPR） applications at 50 mg P/kg （KPRs0） and 250 mg P/kg （KPR250）, mono-calcium phosphate （MCP） application at 50 mg P/kg （MCP50）, and the control without P application. The results showed that KPR50, KPR250, and MCP50 applications significantly increased the dry weight of the ryegrass by 13%, 38%, and 55%, and increased P uptake by 19%, 135%, and 324%, respectively. Compared with MCP50, the relative effectiveness of KPR50 and KPR250 treatments in ryegrass production was about 23% and 68%, respectively. After one season ofryegrass growth, the KPR50, KPR250, and MCP50 applications increased soil-available P by 13.4%, 26.8%, and 55.2%, respectively. More than 80% of the applied KPR-P remained as HC1-P fraction in the soil. Phospholipid fatty acid （PLFA） analysis showed that the total and bacterial PLFAs were significantly higher in the soils with KPR250 and MCP50 treatments compared with KPR50 and control. The latter had no significant difference in the total or bacterial PLFAs. The KPR50, KPR250, and MCP50 treatments increased fungal PLFA by 69%, 103%, and 69%, respectively. Both the principal component analysis and the cluster analysis of the PLFA data suggest that P treatments altered the microbial community composition of the soils, and that P availability might be an important contributor to the changes in the microbial community structure during the ryegrass growth in the paddy soils.