Effects Of Density And Fertility On Spring Maize Yield And CO₂ Emissions From Furrow Harvesting In The Semi-arid Area

To explore the effects of different fertilizer levels and planting density on cropland CO₂ emissions potential of spring maize under the ridge-furrow planting structure,in the semiarid areas of southern progressive 2018 and 2019 field experiment for two consecutive years（two years of the abundance Water year）.Experimental set up three different fertilization gradients,are:nitrogen（pure N）173 kg/ha and phosphate（P₂O₅）88 kg/ha（M）,nitrogen 229 kg/ha and phosphate 115 kg/ha（H）,nitrogen 285 kg/ha With phosphate fertilizer 142 kg/ha（SH）,set three planting densities,respectively 67500 plants/ha（45）,82500 plants/ha（55）,97500 plants/ha（65）.The fertilizer application（SH）and planting density（45）are consistent with local farmers.The effects of different fertilization levels and planting densities on the farmland CO₂ emission rate and the combination of spring maize yield,soil moisture,and heat conditions were further explored to further explore the relationship between soil respiration rate and soil environmental factors.Draw the following results:（1）Effects of different ridge-furrow planting fertilizer and planting density on soil water contentThe soil water storage was affected by different fertilizer application and planting density under the ridge rainwater harvesting model.2018 each experimental treatments of soil water storage 0-200 cm trend after increases and then decreases in spring maize growth period,and the maximum water storage growth period at the time of sowing after 90d（silking）;2019 The water storage capacity of each experiment showed an increase-decrease-increasing trend.Due to the heavy rainfall in the late growth stage of spring corn,the soil water storage of each treatment reached the maximum value at 150days after sowing（maturity period）.Two consecutive years of experiments have shown that under the same planting density,0-200 cm soil water storage decreases gradually during the growth period of spring maize with the increase in fertilization;under the same fertilizer dosage,as the planting density increases,the 0-200 cm soil layer The water storage capacity gradually declined.（2）Effect of different ridge-furrow planting fertilizer on soil temperature and the density of plantingUnder ridge-furrow planting patterns in the spring corn growing period each test temperature treatment 0-10 cm soil layer are presented first and then slowly reduce the rapidly increasing trend,but the temperature difference between the experimental treatment is not obvious.Processing each test soil temperature increased after 2018 when sowing 60d（jointing）to about 23℃,thereafter continuously decreased;2019 due to rainfall,soil temperature reaches after sowing of corn growth when 30 d（seedling）The highest value within.Temperature 0-10 cm soil fertilization treatments in the same planting density,expressed as:M?H?SH,i.e.decreases with increasing the amount of fertilizer;Fertilizers are at the same level and decrease as planting density increases.（3）The effect of different fertilization rates and planting densities of rainwater planting on furrows and ditches on soil CO₂ emissionsUnder the same plant density,with the increase of soil fertility,the respiration rate first decreased and then increased;under the same fertilization amount,the soil planting density increased with the increase of respiration rate.In 2018,the CO₂emission rate of each treatment reached its peak at 60d（joint period）after sowing,in which the respiration rate of H45 treatment was 5.35μmol·m^-2·s^-1,and SH65 treatment was 7.91μmol·m^-2·s^-1 and2019 peaks at about 90d after sowing（silking）,respiration rate H45 treatment is 7.85μml·m^-2·s^-1,for the treatment of respiratory rate M65 9.75μmol·m^-2·s^-1.The cumulative CO₂ emissions in 2018 are less than in 2019,and the cumulative CO₂emissions from H45treatment in 2018 are the lowest,at 17335.14 kg/ha,which is 0.2%and 5.8%lower than that of SH45 and M45 treatments respectively;The cumulative emissions are 18145.03 kg/ha,which is 7.1%lower than SH45.（4）Effects of different fertilizer application and planting density on spring corn yield in furrow rainwater harvestingUnder the same fertilization level,as the planting density decreased,the grain yield increased,and the highest grain yield of H45 treatment in 2018 increased by 7.7%compared to SH45 treatment;grain yield in 2019 SH45 treatment is highest,compared to2018 SH45 Processing reduced production by 42.9%.In 2018 with the same planting density,as the fertilization increased,the grain yield increased,and in 2019 the grain yield decreased.As the fertilization increased,the grain yield increased.（5）Ridge-furrow planting different fertilizer and planting density of CO₂ emissions PotentialUnder the same fertilizer dosage,the CO₂emission intensity of corn increases with the increase of planting density;in the same planting density,the CO₂emission intensity increase as the amount of fertilizer decreases and then increases in each treatment.Soil respiration rate is linearly and negatively correlated with soil water content,and exponentially positively correlated with soil temperature.In summary,under the ridge-furrow planting patterns of different fertilizer nitrogen229 kg/ha and phosphate 115 kg/ha and 67500 planting density can affect soil CO₂emissions by affecting soil moisture and thermal conditions,high yield process and CO₂emission intensity is low,taking into account the economic and environmental benefits can be applied to local production.