Wheat (Triticum astivum L.) is traditionally rainfed in Eritrea. Yields are low because of poor soil management and low water and nutrient inputs. A field experiment was conducted in Akria farm, located in the outskir...Wheat (Triticum astivum L.) is traditionally rainfed in Eritrea. Yields are low because of poor soil management and low water and nutrient inputs. A field experiment was conducted in Akria farm, located in the outskirts of Asmara. The soil was clay loam associated with non-saline shallow water tables fluctuating from 0.4 to 1.2 m depths during the crop season. Wheat variety Wedel Nile was planted in split plot design with four levels of supplementary irrigations (SI) viz. I<sub>1</sub> (rainfed, 0 SI), I<sub>2</sub> (1/3 of full SI), I<sub>3</sub> (2/3 of full SI), and I<sub>4</sub> (full SI) in main plots and three levels of nitrogen viz. N<sub>1</sub> (18 kg N ha<sup>ǃ</sup>), N<sub>2</sub> (50 kg N ha<sup>ǃ</sup>), and N<sub>3</sub> (100 kg N ha<sup>ǃ</sup>) as sub-plots in three replications. Full SI refers to amount of water necessary to replenish soil moisture deficit in the root zone from field capacity to 50% depletion of the available soil moisture. Groundwater table was constant around 0.4 m depth for 32 days from planting and declined slowly thereafter. Wetness around 0.3 m depth was thus near field capacity until second week of December and reduced thereafter with declining water table. Average soil moisture depletion was 94 mm under rainfed and 64 mm under full irrigation. No symptoms of wilting were observed in any of the treatments due to shallow water tables. Upward flux from the water table was 4.6 mm·d<sup>-1</sup> until 30 days from planting, which declined to 0.2 mm·d<sup>-1</sup> when the water table declined below 0.9 m depth. Optimum yield of wheat (5603 kg·ha<sup>-1</sup>) was obtained by application of 58 mm irrigation (I<sub>3</sub>) and 100 kg·ha<sup>-1</sup> nitrogen (N<sub>3</sub>). Total water use for optimum yield of wheat was 382 mm and water use efficiency was 14.7 kg·ha<sup>-1</sup>·mm<sup>-1</sup>. Contribution from water table to the evapotranspiration requirements of wheat was highest (61%) under rainfed (I<sub>1</sub>) and lowest (52%) under full SI (I<sub>4</sub>).展开更多
文摘Wheat (Triticum astivum L.) is traditionally rainfed in Eritrea. Yields are low because of poor soil management and low water and nutrient inputs. A field experiment was conducted in Akria farm, located in the outskirts of Asmara. The soil was clay loam associated with non-saline shallow water tables fluctuating from 0.4 to 1.2 m depths during the crop season. Wheat variety Wedel Nile was planted in split plot design with four levels of supplementary irrigations (SI) viz. I<sub>1</sub> (rainfed, 0 SI), I<sub>2</sub> (1/3 of full SI), I<sub>3</sub> (2/3 of full SI), and I<sub>4</sub> (full SI) in main plots and three levels of nitrogen viz. N<sub>1</sub> (18 kg N ha<sup>ǃ</sup>), N<sub>2</sub> (50 kg N ha<sup>ǃ</sup>), and N<sub>3</sub> (100 kg N ha<sup>ǃ</sup>) as sub-plots in three replications. Full SI refers to amount of water necessary to replenish soil moisture deficit in the root zone from field capacity to 50% depletion of the available soil moisture. Groundwater table was constant around 0.4 m depth for 32 days from planting and declined slowly thereafter. Wetness around 0.3 m depth was thus near field capacity until second week of December and reduced thereafter with declining water table. Average soil moisture depletion was 94 mm under rainfed and 64 mm under full irrigation. No symptoms of wilting were observed in any of the treatments due to shallow water tables. Upward flux from the water table was 4.6 mm·d<sup>-1</sup> until 30 days from planting, which declined to 0.2 mm·d<sup>-1</sup> when the water table declined below 0.9 m depth. Optimum yield of wheat (5603 kg·ha<sup>-1</sup>) was obtained by application of 58 mm irrigation (I<sub>3</sub>) and 100 kg·ha<sup>-1</sup> nitrogen (N<sub>3</sub>). Total water use for optimum yield of wheat was 382 mm and water use efficiency was 14.7 kg·ha<sup>-1</sup>·mm<sup>-1</sup>. Contribution from water table to the evapotranspiration requirements of wheat was highest (61%) under rainfed (I<sub>1</sub>) and lowest (52%) under full SI (I<sub>4</sub>).
