Effect Of Water-Fertilizer-Air-Heat Coupling Of Domestic Reclaimed Water On Photosynthesis,Yield And Quality Of Corn And Rice

This paper addresses the safety of maize and rice irrigated by living reclaimed water in Ningxia.In Xuanhe Town,Shapotou District,Zhongwei City,the effects of water-fertili zer coupling and water-fertilizer-air-heat coupling on maize and rice growth,physiology,yi eld,quality and heavy metals under living reclaimed water irrigation and the effects on so il were systematically studied using a comparative field experiment,a potted orthogonal ex periment and a potted comparison experiment,and the results can provide a The results c an provide a theoretical basis and technical support for the improvement of quality and ef ficiency of maize and rice and the efficient use of water resources in Ningxia.The main research results are as follows.(1)The effect of irrigation rate,irrigation water quality and fertilizer application rate on the growth,physiology,yield,quality and heavy metals of maize irrigated with reclaim ed water and on soil heavy metals was investigated in a comparative field experiment,wh ich showed that the plant height,stalk thickness and fertilizer quantity of maize increased with the increase of irrigation rate and fertilizer quantity under this experiment.The growt h,physiological,yield and quality indicators of maize increased with increasing irrigation r ate.The average plant height at milk maturity was 1.94%higher and the average stalk thi ckness at milk maturity was 2.78%higher than that of Yellow River water.The contents of lead,chromium and arsenic all met the requirements of the National Food Safety Stand ard Limits for Contaminants in Food(GB 2762-2017),and the soil heavy metal content w as much lower than the standard limits of the Soil Environmental Quality Standard for So il Contamination Risk Control of Agricultural Land(GB 15618-2018).(2)The effects of different irrigation water quality and irrigation levels on maize gr owth,physiology,yield,quality and heavy metals as well as on soil heavy metals were in vestigated in a comparative pot experiment,which showed that the growth-physiology-yield indexes of the domestic reclaimed water irrigation treatment were better than those of the Yellow River water irrigation treatment at the same irrigation level.The high irrigation q uota treatment with reclaimed water had the highest kernel yield,100-kernel weight,ears 1 ength and ears thickness than the Yellow River water treatment,and the levels of heavy metals Pb,Cr and As in maize kernels in all treatments met the requirements of the Nati onal Food Safety Standard Limits for Contaminants in Food(GB 2762-2017).Short-term i rrigation with domestic reclaimed water does not cause contamination of maize and soil w ith heavy metals lead,chromium and arsenic.(3)The effect of water-fertiliser-air-heat coupling on growth,physiology,yield,qualit y,heavy metals and on soil heavy metals of potted maize under irrigation with domestic r eclaimed water was investigated using a potted orthogonal experiment.The experiment sho wed that the optimum combination of W3F2R1T3 was determined after a comprehensive s tudy of all aspects of maize growth,physiology,yield and quality,i.e.an irrigation quota of 2970m3/hm2,a fertiliser quota of 214kg/hm2 urea+97.5kg/hm2 compound fertiliser,mul ching and no loosening of the soil,with better plant height indicators.The content of hea vy metals lead,chromium and arsenic in maize seeds all met the standard limits of the N ational Food Safety Standard Limits of Contaminants in Food(GB 2762-2017),and the so il heavy metal content was far below the standard limits of the Standard for Soil Contami nation Risk Control of Agricultural Land for Soil Environmental Quality(GB 15618-2018).Short-term irrigation of domestic reclaimed water will not cause cumulative contamination of soil with heavy metals such as lead,chromium and arsenic.(4)A comparative field experiment was conducted to study the effects of different f ertiliser application rates on the growth,yield,quality and heavy metals of rice under dom estic reclaimed water irrigation,as well as the effects on the soil.The study showed that the growth,yield and quality of rice increased with increasing fertiliser application rates,a nd the appropriate fertiliser application rate under domestic reclaimed water irrigation was 432kg/hm2 diammonium phosphate+360kg/hm2 potassium sulphate.The levels of heavy metals lead,chromium and arsenic in rice seeds were well below the standard limits of th e National Food Safety Standards for Contaminants in Food(GB 2762-2017).The content of heavy metals in the soil is far below the standard limit of the Standard for Soil Polluti on Risk Control of Agricultural Land for Soil Environmental Quality(GB 15618-2018).T he short-term irrigation of domestic reclaimed water will not cause cumulative pollution of soil with heavy metals such as lead,chromium and arsenic.