Effects of composting and application of agricultural waste on soil nutrients, organic corn yield, and nutritional components

To make reasonable use of agricultural waste resources and reduce the amount of chemical fertilizer application, the present study used corn ‘Jingke Nuo 2000’ (A) and ‘Wunongke 1’ (B) as experimental materials and set up five application treatments: no fertilizer, fertilizer, sheep manure, crop straw, and crop straw + sheep manure. The study investigated the changes in soil physical and chemical properties under the different treatments and their effects on corn growth, yield, and nutritional composition to determine the most suitable organic fertilizers for efficient cultivation of organic corn. The results showed that fertilizer treatments resulted in the highest corn yields, reaching 12 376.05 and 12 794.25 kg·ha⁻¹, respectively. The corn yields under sheep manure treatments also reached 8 824.1 and 8 331.0 kg·ha⁻¹, respectively and were significantly higher than those under other treatments, except for the application of pure chemical fertilizers. The alkaline nitrogen and available phosphorus contents in soil treated with sheep manure increased compared to that in soil before sowing, and they were significantly higher than those in other fertilization treatments. The soil pH of all mixed treatments significantly decreased compared to that before sowing, except for no fertilizer treatment, and the soil available potassium content in all other treatments increased compared to that before sowing. Both varieties had the highest dry matter content of 94.8% in sheep manure and chemical fertilizer treatments, respectively. The crude protein content of corn kernels treated with fertilizer was significantly higher than that in other treatments. The highest starch content was in no fertilizer treatment, reaching 72.1% and 72.7%, respectively, and was significantly higher than that in other treatments. The highest crude fat content was in the sheep manure treatments (5.24% and 4.11%, respectively) and was significantly higher than that in other treatments. The yield and nutritional components of different corn varieties and treatments were comprehensively evaluated using membership functions. The two treatments with the highest average membership function ranking were sheep manure treatments, with values of 0.615 and 0.552, respectively. Considering the impact of different fertilization treatments on soil physical and chemical properties, decomposed pure sheep manure is recommended as the most suitable organic fertilizer combination for efficient cultivation of organic corn in the semi-arid area of Hexi.