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在分析了陇东旱塬什字塬区农业资源的基础上,运用“农业生态区域法”(AEZ)估算了该区主要农作物的资源生产潜力,分析了限制农田生产力的主要因素,提出了进一步挖掘潜力的战略途径. 相似文献
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基于三参数最佳动力性换档规律的制定与仿真研究 总被引:1,自引:0,他引:1
通过对汽车自动变速器三参数最佳动力性换档规律的研究,找出最佳动力性换档规律产生循环换档的原因,提出一种改进的动态三参数最佳动力性换档规律。应用MATLAB/SIMIULINK建立的换档规律仿真模型对改进的换档规律进行仿真分析。仿真表明经改进的动态三参数最佳动力性换档规律可以减少循环换档,使汽车获得更好的行驶性能。 相似文献
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《Journal Of Applied Aquaculture》2013,25(1):63-78
Abstract An on-station pond trial was conducted for 6 months to investigate the suitability of mixed-feeding schedules with varying protein levels on the growth of sutchi catfish, Pangasius hypophthalmuswith silver carp, Hypophthalmicthys molitrixwith a view to minimizing the cost of production. Five different feeding regimes employed were: high protein diet (30% protein, H), low protein (15% protein, L), one day low protein diet followed by one day high protein diet (1L/1H), 7 day low protein diet followed by 7 day high protein diet (7L/7H), and 14 day low protein diet followed by 14 day high protein diet (14L/14H). Ten experimental ponds each of 0.008 ha size were divided into 5 treatment groups each with two replicates. Fishes were stocked at the ratio of 80:20 (sutchi catfish:silver carp) at the total rate of 25,000/ha. Feeding rate was calculated only on the basis of sutchi catfish weight only and fish were fed at the rate of 15,10, 8, and 5% of their body weight for 1st, 2nd, 3rd months, and the rest of the experimental period, respectively. The ranges of water quality parameters during the study period were: temperature 22°C to 32.8°C, dissolved oxygen 4.30 to 7.44 mg/L, pH 6.85 to 7.50, and transparency 21.9 to 32.2 cm. The result of the study showed that significantly (P < 0.05) higher fish weight gain was achieved in feeding schedules of H and 1L/1H and lowest with 14L/14H. The feed conversion ratio (FCR) values ranged between 2.06 and 2.51 with H and 1L/1H showing significantly the best FCR. The FCR values were very low when weight of silver carp was considered which ranged between 1.58 and 1.68. The survival (%) of sutchi catfish were lower (78.1 to 82.5%) compared to that of silver carp (90–95%). The total production of sutchi catfish ranged between 3594 and 7095 kg/ha and silver carp ranged between 1777 and 2220 kg/ha. A simple economic analysis showed that fish in 1L/1H fed alternately with low and high protein diets resulted in the highest net profit. The result of the study suggest that for profitable sutchi catfish farming in Bangladesh, farmers can adopt a mixed-feeding schedule of alternated low and high protein diet instead of continuously feeding a high protein diet. 相似文献
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The reported study aimed at developing an integrated management strategy for irrigation water and fertilizers in case of wheat crop in a sub-tropical sub-humid region. Field experiments were conducted on wheat crop (cultivar Sonalika) during the years 2002–2003, 2003–2004 and 2004–2005. Each experiment included four fertilizer treatments and three irrigation treatments during the wheat growth period. During the experiment, the irrigation treatments considered were I1 = 10% maximum allowable depletion (MAD) of available soil water (ASW); I2 = 40% MAD of ASW; I3 = 60% MAD of ASW. The fertilizer treatments considered in the experiments were F1 = control treatment with N:P2O5:K2O as 0:0:0 kg ha−1, F2 = fertilizer application of N:P2O5:K2O as 80:40:40 kg ha−1; F3 = fertilizer application of N:P2O5:K2O as 120:60:60 kg ha−1 and F4 = fertilizer application of N:P2O5:K2O as 160:80:80 kg ha−1. In this study CERES-wheat crop growth model of the DSSAT v4.0 was used to simulate the growth, development and yield of wheat crop using soil, daily weather and management inputs, to aid farmers and decision makers in developing strategies for effective management of inputs. The results of the investigation revealed that magnitudes of grain yield, straw yield and maximum LAI of wheat crop were higher in low volume high frequency irrigation (I1) than the high volume low frequency irrigation (I3). The grain yield, straw yield and maximum LAI increased with increase in fertilization rate for the wheat crop. The results also revealed that increase in level of fertilization increased water use efficiency (WUE) considerably. However, WUE of the I2 irrigation schedule was comparatively higher than the I1 and I3 irrigation schedules due to higher grain yield per unit use of water. Therefore, irrigation schedule with 40% maximum allowable depletion of available soil water (I2) could safely be maintained during the non-critical stages to save water without sacrificing the crop yield. Increase in level of fertilization increases the WUE but it will cause environmental problem beyond certain limit. The calibrated CERES-wheat model could predict the grain yield, straw yield and maximum LAI of wheat crop with considerable accuracy and therefore can be recommended for decision-making in similar regions. 相似文献