Impact of amendments on the physical properties of soil under tropical long-term no till conditions

Tropical regions have been considered the world's primary agricultural frontier; however, some physico-chemical deficiencies, such as low soil organic matter content, poor soil structure, high erodibility, soil acidity, and aluminum toxicity, have affected their productive capacity. Lime and gypsum are commonly used to improve soil chemical fertility, but no information exists about the long-term effects of these products on the physical attributes and C protection mechanisms of highly weathered Oxisols. A field trial was conducted in a sandy clay loam (kaolinitic, thermic Typic Haplorthox) under a no-tillage system for 12 years. The trial consisted of four treatments: a control with no soil amendment application, the application of 2.1 Mg ha-1 phosphogypsum, the application of 2.0 Mg ha-1 lime, and the application of lime + phosphogypsum (2.0 + 2.1 Mg ha-1, respectively). Since the experiment was established in 2002, the rates have been applied three times (2002, 2004, and 2010). Surface liming effectively increased water-stable aggregates > 2.0 mm at a depth of up to 0.2 m; however, the association with phosphogypsum was considered a good strategy to improve the macroaggregate stability in subsoil layers (0.20 to 0.40 m). Consequently, both soil amendments applied together increased the mean weight diameter (MWD) and geometric mean diameter (GMD) in all soil layers, with increases of up to 118 and 89%, respectively, according to the soil layer. The formation and stabilization of larger aggregates contributed to a higher accumulation of total organic carbon (TOC) on these structures. In addition to TOC, the MWD and aggregate stability index were positively correlated with Ca2+ and Mg2+ levels and base saturation. Consequently, the increase observed in the aggregate size class resulted in a better organization of soil particles, increasing the macroporosity and reducing the soil bulk density and penetration resistance. Therefore, adequate soil chemical management plays a fundamental role in improving the soil's physical attributes in tropical areas under conservative management and highly affected by compaction caused by intensive farming

The dominant Anopheles vectors of human malaria in the Asia-Pacific region: occurrence data, distribution maps and bionomic précis

<p>Abstract</p> <p>Background</p> <p>The final article in a series of three publications examining the global distribution of 41 dominant vector species (DVS) of malaria is presented here. The first publication examined the DVS from the Americas, with the second covering those species present in Africa, Europe and the Middle East. Here we discuss the 19 DVS of the Asian-Pacific region. This region experiences a high diversity of vector species, many occurring sympatrically, which, combined with the occurrence of a high number of species complexes and suspected species complexes, and behavioural plasticity of many of these major vectors, adds a level of entomological complexity not comparable elsewhere globally. To try and untangle the intricacy of the vectors of this region and to increase the effectiveness of vector control interventions, an understanding of the contemporary distribution of each species, combined with a synthesis of the current knowledge of their behaviour and ecology is needed.</p> <p>Results</p> <p>Expert opinion (EO) range maps, created with the most up-to-date expert knowledge of each DVS distribution, were combined with a contemporary database of occurrence data and a suite of open access, environmental and climatic variables. Using the Boosted Regression Tree (BRT) modelling method, distribution maps of each DVS were produced. The occurrence data were abstracted from the formal, published literature, plus other relevant sources, resulting in the collation of DVS occurrence at 10116 locations across 31 countries, of which 8853 were successfully geo-referenced and 7430 were resolved to spatial areas that could be included in the BRT model. A detailed summary of the information on the bionomics of each species and species complex is also presented.</p> <p>Conclusions</p> <p>This article concludes a project aimed to establish the contemporary global distribution of the DVS of malaria. The three articles produced are intended as a detailed reference for scientists continuing research into the aspects of taxonomy, biology and ecology relevant to species-specific vector control. This research is particularly relevant to help unravel the complicated taxonomic status, ecology and epidemiology of the vectors of the Asia-Pacific region. All the occurrence data, predictive maps and EO-shape files generated during the production of these publications will be made available in the public domain. We hope that this will encourage data sharing to improve future iterations of the distribution maps.</p

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Not AvailableMulches, organic or inorganic in nature, favorably moderate soil's hydrothermal regime, assume significance in the context of climate change. The in-situ mulching under conservation agriculture avoids crop residue burning. Besides improving crop growth, moderation of soil moisture regime, buffering soil temperature fluctuations, facilitating soil aeration, seedling emergence, improving root growth, efficient water and nutrient use by crop plants it also improves the environment by facilitating carbon sequestration and reducing greenhouse gas emissions from the soil. Appropriate policy decisions to overcome limitations in adoption of conservation agriculture and mulching are required by providing technical and financial support to the farmersNot Availabl

Strategies for promoting water and nutrients use efficiencies

Not AvailableNutrient and water are the most crucial inputs for agricultural production. Rainfed area occupying about 65%(89 M ha) of the cultivated land in India accounts for only 40% of total food production, whereas irrigated area covering 35%(53 M ha) of the cultivated land contributes 60% to the national food basket. Low water use efficiency (WUE) however, has been the concern along with the decreasing availability of water for agriculture. For efficient conservation and utilization of these vital resources, suitable state of the art agro-techniques need to be promoted. As a universal phenomenon, water losses start from the moment rain drops fall on the ground. In an irrigation system, water is lost during conveyance by evaporation, transpiration by weeds and seepage, while lost in the field by deep percolation beyond root zone and by runoff at end of border and furrows. The magnitudes of these losses vary widely on account of the different physiographic features, water control and conveyance structures and management practices. Vagaries of monsoon and declining water table due to over exploitation have resulted in shortage of fresh water supplies for agricultural use, which too calls for an efficient use of this resource. Low efficiency of inputs/fertilizer use is another key factor pushing the cost of cultivation and pulling down the profitability in farming. Total factor productivity (TFP), an important measure to evaluate the performance of a production system, is showing declining trend which is a serious issue. A fatigue in the ratio between the inputs and output is indicative of TFP deceleration with concomitant unsustainability of crop productivity. The challenge …Not Availabl

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Not AvailableConserving soil moisture in the rainfed region is a challenging task as it plays a significant role in crop productivity and livelihood security of rainfed farmers. The soil moisture conservation practices (MCPs) coupled with the addition of root augmenting nutrition are crucial for sustaining crop yields and maintaining soil phosphorus (P) in a rainfed Vertisol of Central India. Thus, a study was conducted to evaluate the long-term effect of MCPs and P application in maize–chickpea in a Vertisol. A five-year study showed that the MCPs integrated with P nutrition significantly helped in growing chickpea (Cicer arietinum) without irrigation or with limited irrigation. Under the normal rainfall conditions such as normal onset time, distribution and cessation time during the experimentation, the MCPs proved useful in obtaining chickpea yields in the range of 776 to 933 kg ha−1. The best MCP was the practice of late intercultural operations + Gliricidia cover in the inter-row spaces of standing maize (@ 5 t ha−1 fresh weight basis) + maize stover application (after sowing up to germination), which recorded higher chickpea grain yield (932 kg ha−1) on account of higher moisture content in the soil and reduced stress in the plants. Another comparable treatment was Gliricidia cover + one pre-sowing irrigation of 6 cm for chickpea, which recorded 933 kg ha−1 of chickpea yield. Both the treatments recorded significantly higher yields than the under control (637 kg ha−1). We also found that the application of Gliricidia cover on the soil surface coupled with either pre-sowing irrigation and/or late intercultural operations had beneficial effect on soil physical conditions increasing soil moisture which in turn affected the crop growth. Under normal monsoon years, the best treatments (MCP4 and MCP5) recorded around 46% higher chickpea yield as compared to the control. It is concluded that these soil MCPs are very useful in rainfed areas for sustaining crop yieldNot Availabl

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Not AvailableDistillery effluent, a waste by-product of distillery industries, is usually applied to arable land near the distilleries as irrigation water or as a soil amendment. To evaluate the effect of distillery effluent, both spent wash (SW) and post-methanated effluent (PME), on soil organic carbon and aggregate stability, a field experiment on a soybean (Glysine max L.)–wheat (Triticum aestivum L.) system was conducted for five years on a Vertisol of central India. The treatments were control (no fertilizer or manure or SW or PME, T1), 100% NPK + farmyard manure (FYM) @ 4 Mg ha−1 to soybean (T2), four graded levels of SW, viz., 2.5 cm SW to soybean and none to wheat (T3), 2.5 cm SW to soybean and 1.25 cm to wheat (T4), 5 cm SW to soybean and none to wheat (T5), 5 cm SW to soybean and 2.5 cm to wheat (T6), and four graded levels of PME, viz., 2.5 cm PME to soybean and none to wheat (T7), 2.5 cm PME to soybean and 1.25 cm to wheat (T8), 5 cm PME to soybean and none to wheat (T9), 5 cm PME to soybean and 2.5 cm to wheat (T10). The organic carbon of the surface (0–15 cm) soil that received either PME or SW (treatments T3–T10), was significantly (P < 0.05) higher than in treatments T1 and T2. The mean weight diameter (MWD) of water stable aggregates in this soil layer was also significantly higher in treatments T3–T10, compared with T1 and T2. The MWD showed a positive linear relationship with the organic carbon content of the soil (R2 = 0.54 * *). The proportion of macro-aggregates was higher in SW treated plots than PME, no distillery effluents and NPK + FYM treatments. However, the micro-aggregates showed the reverse trend. The macro-aggregate-associated carbon was higher in SW treated plots. It was highest in T6 and lowest in T1. The plots receiving the PME and SW showed increased soil organic carbon, MWD, percentage macro- and micro-aggregate-associated carbon than T1 and T2. Application of distillery effluents increased the aggregate stability of the Vertisol through enhanced soil organic carbon as well as the aggregate-associated carbon. So application of SW or PME could be a viable option for soil aggregate stability and enhanced productivityNot Availabl

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