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Abstract: Groundwater irrigation consumes considerable energy as well as water resources across the globe. Using a case study from Iran, this paper explores how enhanced farm water management can help in reducing groundwater exploitation and subsequently limiting energy consumption and the carbon footprint of the groundwater economy. Groundwater use for irrigated agriculture in Iran has increased vastly over the last three decades. We estimate that groundwater pumping consumes 20.5billionkWh electricity and 2 billion liters of diesel and contributes to 3.6% of the total carbon emission of the country. Thus there is an opportunity to reduce energy use and carbon emissions by pumping less water. However, groundwater use remains important for food security. To identify opportunities for water conservation within agricultural fields, the SWAP model was applied to simulate crop growth and field water balance for three major irrigated crops, i.e. wheat, maize, and sugar beet in the Gamasiab River Basin, one of the highest groundwater using irrigated areas of Iran. The model simulations showed that by adopting improved irrigation schedules and improving farm application efficiencies, water productivity will increase, and irrigation water withdrawals from groundwater can be reduced significantly with no reduction in yields. While these improvements may or may not result in water saving and retarding the ground water decline, depending on the fate of excess application, they will have significant water quality, energy, and carbon implications. Such reduction in irrigation application can result in 40% decline in energy consumption and subsequently carbon emission of groundwater use. [Copyright &y& Elsevier]

Abstract: Seed placement and failure to establish a uniform plant stand are critical problems associated with conservation tillage production of corn (Zea mays) following wheat (Triticum aestivum) in Iran. Our objectives were to evaluate the performance of a conventional corn planter (with runner type openers) equipped with row cleaners and to demonstrate for local farmers an affordable method for reduced tillage corn production. The reduced tillage system studied consisted of disking followed by chisel plowing and another disking ahead of planting. A ground-driven row cleaner was fabricated and mounted to each unit of a common pneumatic single seed planter and used to plant at three forward speeds (4, 7, and 10kmh−1) into no- (NR), half- (HR), and whole- (WR) residue plots. This compares to a typical system of complete removal or burning the previous wheat residue in the region. The amount of residue retained in the row, depth of seed placement, emergence rate and three indices of uniformity in seed spacing were determined. Row cleaners performed best at the highest forward speed, retaining an average residue cover of 920kgha−1 compared to 1350kgha−1 for plots planted without using row cleaners. This 430kgha−1 more residue removal was a significant improvement with regard to soil–seed contact. For the HR and WR plots, residue removal averaged 45% and 70% of that present before planting, suggesting that the row cleaners will work more effectively at high residue conditions. Without row cleaners, initial residue levels resulted in a shallow planting depth, but when row cleaners were used, planting depth was maintained near the target depth (5cm). The desired planting depth was also obtained at 7kmh−1 in the HR plots. Row cleaners significantly increased plant emergence rate with the maximum (3.5plantsd−1 m−1) being observed for seeds planted at 4kmh−1 in the HR plots. This agrees with others who showed high residue reduces plant emergence and grain yield. Planting with row cleaners into HR plots at 7kmh−1 resulted in the lowest miss and precision indices comparable to those of a no-residue plot (16.5% and 17.5%, respectively), and a quality of feed index as high as 69% was obtained at similar conditions. Our results indicate that equipping available planters with row cleaners can result in a successful reduced tillage corn production system and thus satisfy both farmers and authorities promoting conservation tillage. In addition to the environmental benefits of the proposed system, it is expected that the savings in time, fuel and labor would offset the cost of row cleaners. [Copyright &y& Elsevier]

• Water conservation is the best way to increase water management efficiency in agriculture and reduce potential negative environmental impacts. • Residue improves soil tilth and adds organic matter to the soil as it decomposes. • Crop residue can reduce the rate of water evaporation and runoff, increase penetration of water and therefore improve soil water conservation. Wheat (Triticum aestivum L.) residues and water management are major problems in southern part of Iran where irrigated wheat-corn (Zea mays L.)-wheat rotation is a common practice. A 2-year (2015–2016) field experiment was conducted as a split plot design with four replications to determine the influence of different irrigation regimes (50, 70, and 100% of water requirement) and wheat residue rates (0, 25, and 50%) incorporation into the soil on sweet corn (Zea mays L V. Saccharata) growth, grain yield, and some soil properties at School of Agriculture, Shiraz University, Shiraz, Iran. The results showed that the highest plant height (187.12 cm) and leaf area index (3.49) were obtained when the crop was normally irrigated (100% of water requirement) and sown into the 25% incorporated wheat residues. Furthermore, canned yield (68%) and water use efficiency (WUE) increased with normal irrigation and 25% residue incorporation compared to the 50% wheat residue rate. The highest grain protein (14.67%) was achieved under incorporation of either 25 or 50% wheat residue into the soil, while the highest grain sugar (2643.5 mg g−1) was obtained when the crop was moderately irrigated (70% of water requirement) with 25% residue incorporation into the soil. The highest soil nitrogen (N) and soil organic carbon (SOC) were achieved with normal irrigation and 50% residue incorporation in both years.In general, adopting an adequate rate of wheat residue (between 25%–50%) accompanied by decreasing irrigation volume to 70% water requirement of corn is recommended in semi-arid agroecosystems. [ABSTRACT FROM AUTHOR]