A M; M KH; A A; P SH
Abstract
In order to study the effect of limited irrigation on increasing the yield and water productivity of soybean, a split plot experiment based on a randomized complete block design with four replications was conducted in two cropping seasons of 2013 and 2014, in Rasht. Three irrigation treatments including ...
Read More
In order to study the effect of limited irrigation on increasing the yield and water productivity of soybean, a split plot experiment based on a randomized complete block design with four replications was conducted in two cropping seasons of 2013 and 2014, in Rasht. Three irrigation treatments including two irrigations (I2): irrigation at flowering and pod formation stages, three irrigations (I3): irrigation at flowering, pod formation and ripening stages, and rainfed (I0): as control treatment were allocated to the main plots and three soybean genotypes including Williams (V1), L17 (V2), and Habbit (V3) to subplots. During the critical growth stages of the plant, based on the irrigation treatment and considering the precipitation and available moisture in the root zone, only one irrigation was applied (I1) in 2013 while Williams and Habbit genotypes were, respectively, at pod formation and at flowering stage. But, in 2014 crop season, considering the lower precipitation, all irrigation treatments were conducted. Yield and yield components were measured at seed ripening time. The results showed that the limited irrigation in both years improved yield and yield components of all soybeans genotypes. The highest average grain yield in both crop seasons were obtained with I1V2 and I3V2 treatments, being 4616 and 4198 kg/ha, respectively. In both cropping seasons of 2013 and 2014, L17 genotype had the highest average grain yield compared with the other two genotypes, being 3932 and 3000 kg/ha, respectively, therefore, it can be recommended for planting in Rasht region. In 2013 and 2014 crop seasons, respectively, I1V2 and I3V2 treatments had the highest water productivity, corresponding to 1.72 and 0.97 kg/m3.
m gh; m kh; m b; p sh
Abstract
Today, use of drip irrigation systems for row crops is widespread. One of these systems is subsurface drip irrigation. Knowing the dimensions of the wetting pattern is essential for drip irrigation system design. To design a proper system, as field experiments are time consuming and expensive, using ...
Read More
Today, use of drip irrigation systems for row crops is widespread. One of these systems is subsurface drip irrigation. Knowing the dimensions of the wetting pattern is essential for drip irrigation system design. To design a proper system, as field experiments are time consuming and expensive, using computer models is recommended. In this regard, the present study examined the performance of three models including empirical Kandelous et al. model, analytical WetUp, and numerical HYDRUS-2D models in subsurface tape irrigation. Treatments included three volumes of water i.e. 10, 15, and 20 liters per meter length of tape and three installation depths of 10, 20, and 30 cm, in three replications. Comparison between the measured and simulated wetting dimensions were made by using four statistical indices i.e. RMSE, nRMSE, CRM, and MAE. RMSE values of horizontal wetting extension for Kandelous et al and HYDRUS-2D models were 0.051 and 0.066 m, respectively, while for vertical wetting extension, the values of RMSE were 0.052 and 0.078 m, respectively. nRMSE values of horizontal wetting extension for Kandelous et al. and HYDRUS-2D models were 15.46% and 19.71 %, respectively, being in class ‘good’. nRMSE values of vertical wetting extension for Kandelous et al and HYDRUS-2D models were 15.99 and 23.74 %, respectively, considered as ‘good’ and ‘fair’, respectively. Statistical indices calculated for WetUp model was not in acceptable range. For horizontal and vertical wetting dimensions, CRM and MAE indices for Kandelous et al model were the lowest values. Overall, the Kandelous et al model had the best estimation.
h p; m kh; m.h b; p sh
Abstract
As irrigation system installation is expensive and time consuming, it would be better to have an estimate of the water content provided by the system in the active root zone before designing an irrigation system. In this study, HYDRUS-2D performance was assessed under a tape irrigating in-situ with a ...
Read More
As irrigation system installation is expensive and time consuming, it would be better to have an estimate of the water content provided by the system in the active root zone before designing an irrigation system. In this study, HYDRUS-2D performance was assessed under a tape irrigating in-situ with a heavy textured and relatively heterogeneous soil in Rasht region. Three different flows i.e. 2.5, 5, and 6 L/h/m and four irrigation times i.e. 1, 2, 3, and 4 hours were considered as the main treatments with three replications. Measured data were compared with the simulated results for both the whole soil profile and the part under the tape using two statistical indices, i.e. RMSE and efficiency factor (EF). The model performance was evaluated as good, with a low average RMSE of 0.0123 and 0.0236 cm3/cm3 for the whole soil profile and under the tape, respectively, with the corresponding average EF values of 77% and 76%, for this soil texture. Overall, the model could satisfactorily simulate soil moisture in a heavy textured and heterogeneous soil.