| The Northern slope region of Qinling Mountains is the main kiwifruit production area in Shaanxi province, and has the largest planting area and kiwifruit yield in China. But with the development of kiwifruit industry, the excessive input of nutrients has become much severe which is contributing towards the loss of nutrient resource. Steep slope and abundant rainfall further speedup the loss and the nutrients especially nitrogen is accumulating deep within the soil. Therefore, in order to control and reduce the nutrients loss caused by excessive fertilization, management of the fertilizer inputs and irrigation water is very important which will also help in decreasing the agricultural non-point source pollution in the region.A survey was conducted in Yujiahe catchment located in the Zhuyu Town of Zhouzhi County in the Shaanxi province to assess the status of N input in soil used for the growth of kiwifruit orchards. Soil samples from mature kiwifruit orchards were collected both before and after the rainy season in order to know the net impact of rainfall on the accumulation and movement of NO3--N in the soil profile of sloppy kiwifruit orchards. Keeping in view the above, we arranged the experiment to study the effect of drip fertigation on the kiwifruit yield and quality and its role in movement of soil nutrients, the results of which are stated below:1. The results showed that the excessive application of N in the catchment was very severe. The surplus amount of N applied was up to 1195 kg·ha-1 with residual NO3--N being 827 kg·ha-1 in the 0-200 cm soil profile while 52% of the NO3--N accumulation occured in 100-200 cm soil profile. The accumulation of NO3--N in an orchard was dependent on the locations; compared to the upslope, more of NO3--N was accumulated in downslope in the 0-200 cm soil profile. After a rainy season, the increase in NO3--N leaching in soil profile was obvious and more NO3--N leaching was recorded in downslope in the same orchard. It is concluded that the excessive addition of N to kiwifruit orchards in Yujiahe catchment resulted in high accumulation of NO3--N in the soil. The NO3--N leaching in soil profiles during the rainy season was also severe. It would not only increase the loss of N fertilizer resource, but also increase the potential threat to the quality of both surface and groundwater.2. There was no difference in the kiwifruit yield between conventional flooding irrigation fertilization treatment and drip fertigation treatment, but compared with conventional flooding irrigation fertilization treatment, increase in the soluble saccharide, sugar-acid ratio and Vc of kiwifruit was observed under drip fertigation treatment. Meanwhile, drip fertigation treatment also significantly increased the utilization of nutrient and water with saving rates of nitrogen and water being 58% and 60%, respectively. Fertilizer partial productivity（PFP）、irrigation water use coefficient（i WUE） and water use coefficient（WUE） were also significantly increased by 151%、171% and 37%,respectively.3. The soil mineral N during different growth period of kiwifruit was suitable for the kiwifruit growth with drip fertigation treatment and was significantly lower than the conventional flooding irrigation fertilization treatment. Compared with the conventional flooding irrigation fertilization treatment, drip fertigation treatment significantly decreased the soil NO3--N accumulation（509 kg·ha-1） in kiwifruit in 0-200 cm soil profile. No matter before or after the rainy season, the O.M., total N, available P, available K and nitrate accumulation in 0-200 cm soil profile in the downslope was higher than that of upslope indicating that the existence of the slope resulted in the unbalanced distribution of nutrients. But compared with the nutrient concentration before rainy season, there was no significant change for difference between upslope and downslope with different treatment after the rainy season. |
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