The quartz sand filter medium used in micro-irrigation media filters has the disadvantages of short filtration cycle, surface filtration, and mining pollution. Selecting resources as new filter media is essential to improve the performance of the media filter and boost sustainable development. In this study, the traditional quartz sand filter medium and two new filter media were selected, and their corresponding filtration performances were comparatively studied. The influence of the type, particle size, and height of the filter medium on filtration performance was evaluated. The sediment content and distribution based on the size of particles in quartz sand, crushed glass, and glass bead filter layers was measured and analyzed. The hydraulic performance of different filter columns was analyzed. The results showed that for a given particle size, quartz sand exhibits the best sediment retention ability. This promoted the aggregation of small sediment particles into larger ones, whereas the crushed glass and bead glass filter layers promoted the splitting of large sediment particles into smaller ones, which enabled the reduction of blockage during the micro-irrigation process. The filtration rate of the quartz sand filter column exhibited the least fluctuation relative to crushed glass and glass bead filter media, and the pressure in each column exhibited a linear incremental change. In summary, glass microbeads are not suitable as filter material, crushed glass is suitable for general micro-irrigation systems, and quartz sand is suitable for micro-irrigation systems with elaborate filtration requirements. The findings of this study can provide theoretical guidance for the selection of the micro-irrigation filter material.
Light and small sprinklers were used to irrigate winter wheat fields. The distribution and migration of water and nitrogen in soil during winter wheat growth period were analyzed. Moreover, the growth traits of winter wheat were monitored. It is demonstrated that water–fertilizer coupling effect had a significant impact on the migration of water and nitrogen in soil and the growth traits of winter wheat under conditions of light and small sprinklers. Under the same condition of irrigation quota, although the content of moisture in soil was slightly reduced with the increase of the amount of fertilizer, the impact of the amount of fertilizer on the content of moisture in soil is much more insignificant than that of irrigation quota. The content of nitrate nitrogen (NO3--N) in soil was increased with an increasing amount of fertilizer, especially when the value of irrigation quota was low. On the other hand, under the same condition of amount of fertilizer, the content of nitrate nitrogen (NO3--N) in soil was decreased with an increasing value of irrigation quota, especially when the value of irrigation quota was high. Hence, an ultra-high value of irrigation quota will aggravate the leach of nitrate nitrogen in soil. The water–fertilizer coupling effect and yield of winter wheat could be optimized by improving irrigation scheme, optimizing irrigation quota, and optimizing the amount of fertilizer.