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The characteristics of controlled-release fertilizer are long effective time, high nutrient use efficiency, little environmental pollution, convenient to use, and so on. So it is widely applied to various types of soil and crop. The promotion and application of controlled-release fertilizer will help to develop the high-yield, high-efficiency, high-quality agriculture, it is also has great significance for economic growth, energy conservation and pollution reduction. The controlled-release fertilizers used in this study were manufactured in Shandong Kingenta Ecological Engineering Co., Ltd. Under potato and maize relay cropping system, field experiment was conducted to study the effects of controlled-release fertilizer on topsoil nutrients, vertical distribution of soil nutrient, soil enzyme activities, crop growth, crop yield, nutrient use efficiency, and economic benefit. The optimum amount of controlled-release fertilizer is determined primarily. It is provided the theoretical support and technical basis for the application of controlled-release fertilizer under potato and maize relay cropping system. The main results were as followed:1. Compared with ordinary fertilizer, the content of available N in arable soil was increased and available N leaching was decreased significantly by the application of controlled-release fertilizer, and the content of NO3-N under the arable soil was decreased by an average of 28.60%. Furthermore, P and K leaching were inhibited to a certain degree, which respectively decreased by an average of 5.72% and 7.03%. The nutrient content in arable soil was increased by the treatments of controlled-release fertilization, and the reduction treatment (80% of the convention treatment) has the best effect. Besides, deep fertilizing was superior to low fertilizing. The promotion effect of controlled-release fertilizer on the activities of phosphatase, sucrase and urease were significantly better than ordinary fertilizer, respectively increased by 10.2%, 14.62%, 15.7%, and deep fertilizing was better. But the controlled-release fertilizer could cause some degree of inhibition on catalase activity which was decreased by an average of 11.13%. 2. Compared with ordinary fertilizer, the plant height, stem diameter and chlorophyll of potato was significantly increased by the application of controlled-release fertilizer, which respectively increased by 5.94%, 9.04% and 5.55%, the numeral of maize were 5.39%,6.76%,4.42%. Furthermore, when the amount of controlled-release fertilizer was reduced by 20%, there is no significant change on the promotion effect. Compared with low fertilizing, deep fertilizing of controlled-release fertilizer was more conducive to increase the growth index of crop. Compared with ordinary fertilizer, the potato and maize were significantly increased by the application of controlled-release fertilizer. The added potassium treatment had the highest production rate of potato, and the convention treatment had the highest production rate of maize. Besides, the production rate of all the deep fertilizing treatments was higher than the low fertilizing treatments.3.Compared with ordinary fertilizer, the apparent recovery efficiency of applied nitrogen, the potato ratio of output to input, net income per hectare of potato,the maize ratio of output to input, net income per hectare of maize were significantly increased by the application of controlled-release fertilizer, which respectively increased by 16.32%, 47.02%, 16.38%, 33.55%, 20.79%. The nitrogen use efficiency and the ratio of output to input of the reduction treatment (80% of the convention treatment) were the highest of all. Compared with low fertilizing, deep fertilizing has the higher nitrogen use efficiency and the obviously economic efficiency.4. The application of 480kg per hectare of the 21-11-16 controlled-release fertilizer was the optimal treatment based on this experiment, for it has the minimal effects on soil environment, the highest nitrogen efficiency, and the biggest economic efficiency. In the future studies, it is needed continue to adjust nutrient formula and the application amount, in order to make it more anastomotic to the crop needs.
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