Effect Of Cattle Dung Composting On Weed Seed Inactivation And Seed Viability

With the rapid development of livestock and poultry industry in China,poultry manure production increased year by year.Environmental pollution and waste of resources will be caused without proper disposal of feces.Aerobic composting can transform livestock and poultry waste into high-quality organic fertilizer and reduce environmental pollution,which can achieve the harmlessness of livestock and poultry manure.However,during the aerobic composting process of animal manure,may be due to some reasons for composting material to lead into some weed seeds,such as raw materials include animal waste and auxiliary materials,animal handling,carrying and stormy weather.If the composting does not kill the weed seeds,as the compost is applied to the soil,it is possible to bring weeds into the field,affecting the normal growth of crops and the health of human and livestock.In this study,fresh cattle dung was used as raw material,which was collected from a cattle farm in Northwest A&F University teaching base,and the sawdust of Yangling wood processing plant was used as a conditioner,a 45-day simulated aerobic composting process was carried out with biochemical incubator.Eight kinds of weed seeds?Amaranthus paniculatus,Bidens pilosa,Barnyardgrass,Datura,Field bindweed,Setaria,Bermuda grass and Ryegrass?,two kinds of vegetable seeds?tomato and rape?and two kinds of grain crop seeds?corn and wheat?were put into the compost material before the start of composting process.The purpose of this study was to investigate the inactivation of weeds and other seeds and the changes of seed viability in compost.Meanwhile,the influence degree of various physicochemical index changes on seed viability was explored through the multiple regression.The main conclusions of this study are as follows.?1?The simulated composting of this experiment reached harmless standards and eventually achieved maturity,besides,the changes of the indicators were in line with the basic requirements of composting.The effect of composting process on weeds and other seed viability can be considered as a reference for natural compost.The initial stage of the compost is the optimum period to destroy weed seeds.?2?Seeds put into the material are dying with the composting process,all of the seeds were inactivated within 110 hours?the temperature is below 60??except field bindweed.So weed seeds and other seeds will be inactivated in the cattle dung composting when the temperature reached 60?during thermophilic phase.?3?There is significant correlation between the various physical and chemical indexes during composting,pH,NH₄⁺-N,acetic acid and DTPA-heavy metals were the main factors influencing the seed germination and had the higher contribution of the phytotoxicity.Multiple regression of compost index and seed viability analysis showed that the influence of temperature on seeds viability is maximum.Except for the temperature,seed viability can be significantly affected by other factors,such as pH,EC,total heavy metal and DTPA-heavy metals,and they are also the main causes of seed inactivation.In a word,the livestock manure thermophilic aerobic compost can effectively destroy weed seeds,and the organic compost generally will not bring weeds to the field.