Effect of large-scale pig farm waste water on wheat yield and quality

With the rapid development of China’s large-scale pig farms, increasing manure and sewage discharge is causing severe environmental pollution that in turn threatens the sustainable development of large-scale pig farming. The utilization of sewage, a kind source of nutrient, by combined pig farming with cropping is the best solution to this problem. As sewage utilization in farmlands lacked systematic research, a field experiment was conducted to study sewage effect on yield and quality of wheat. The results of the study could provide the scientific basis for efficient wheat production that supported large-scale pig farming. The sewage used in the experiment contained 1 000 mg·L^?1 of total nitrogen, 540 mg·L^-1 of available nitrogen and 779 mg·L^-1 of available phosphorus. The experimental treatments consisted of different combinations of sewage (0 m³·hm^?2, 30 m³·hm^?2, 60 m³·hm^?2, 90 m³·hm^?2 and 120 m³·hm^?2) and nitrogen 0 kg(N)·hm^?2, 30 kg(N)·hm^?2, 60 kg(N)·hm^?2 and 90 kg(N)·hm^?2 application rates plus conventional base fertilizer at winter wheat booting stage. The results showed that wheat grain yield under 30 m³·hm^?2, 60 m³·hm^?2 and 90 m³ respectively. Wheat grain yield under the conventional fertilizer treatment was 8 305.52 kg·hm^?2. Yield under zero-topdressing or 30 kg(N)·hm^?2 nitrogen treatment was lower than that under conventional fertilizer application. This demonstrated that sewage use must be combined with certain amounts of fertilizer to get desired outputs. Grain protein content under zero-nitrogen or 30 kg(N)·hm^?2 nitrogen application was below 13%, the lower limit of medium-gluten wheat requirement. Taking both yield and quality into account, combination of 60 m³·hm^?2 sewage and 90 kg(N)·hm^?2 nitrogen fertilizer or 90 m³·hm^?2 sewage and 60 kg(N)·hm^?2 nitrogen fertilizer was a suitable fertilization program. If sewage field carrying capacity and reduction in chemical fertilizer were taken as additional factors, then the combination of 90 m³·hm^?2 sewage and 60 kg(N)·hm^?2 nitrogen fertilizer application was most suitable for high yield, good quality and efficient wheat production in the study area.