Conservation Tillage Improves Soil Nutrients And Reduces Nitrogen And Phosphorous Losses In Farmlands In Southern China And Ghana

Monitoring nitrogen（N）and phosphorous（P）losses on farmland is essential for the prevention of agricultural non-point source pollution（NPS）.This study was conducted in the southern part of China and Ghana to determine the effect of conservation and conventional tillage techniques on soil properties,nutrient movement（leaching）,growth and yield of rice as well as the effect of such tillage methods on soil N and P losses.Results from Lianping suggest that MTDS and NTDS improved soil physical and chemical properties by ensuring adequate retention of these properties at the 0-20 cm soil depth.Varied levels of soil nutrients（TN,TP,NO₃^--N and NH₄⁺-N）at40-100 cm soil depth were recorded among all tillage techniques.However,low levels of N and P losses in runoff and drainage water were recorded under NTTS and NTDS compared to CT.Our results,therefore,suggest that conservation tillage techniques such as MTDS and NTDS are the most suitable tillage technique for improving soil nutrients and reducing agricultural non-point source（Ag NPS）N and P losses while providing a good ecological environment.Results from the rice field in Ghana showed that after two cropping seasons,soil bulk density was in the order of（ZTTS=ZTDS）＞RTDS＞RTTS＞CT.ZTDS and ZTTS were associated with significantly higher levels of nutrients at the top soil（0-20cm）as compared with the rest of the treatments.Plant height was in the order of CT>RTTS=ZTTS>RTDS>ZTDS.The highest grain yield was recorded by both CT and ZTTS significantly different from the rest of the treatments.ZTDS,recorded the highest stover yield for both years.Subsequently,CT was associated with high release of potential pollutant loads which could lead to Ag NPS pollution as evident in the high nutrient loss.Comparative results from Baitang-China and Central Agricultural Research Station（CARS）-Ghana suggest improved soil bulk density,p H and enhanced soil nutrients at the 0-20 cm soil surface and a reduction in Ag NPS pollutant loads under MTDS and NTDS in Baitang-China whereas MTTS and NTTS recorded similar results in CARS-Ghana.Comparatively,CT in Baitang-China recorded high bulk density（1.45%）than bulk density in CARS-Ghana with the latter also recording highest soil p H.Subsequently,plant height,panicle number and grain yield of rice were enhanced under the conservation tillage methods.Moreover,MTDS and MTTS in Baitang-China,NTDS and NTTS in CARS-Ghana showed improved soil properties,minimize the release of potential NPS N and P pollutants into the environment and further enhance the growth and yield of rice.Also,Results from Pingtan suggest that bulk density had no significant difference among treatments.Very low soil p H was found for NT at harvest.Highest nutrient levels were recorded under the CT with the exception high NO₃-N and NH₄⁺-N recorded under NT.Highest bacteria count was recorded under NT whilst highest fungal and actinomycetes were recorded under CT.We conclude that all the tillage technologies affected different soil parameters differently under the prevailing condition.However,for sustainable crop production,tillage methods such as NT and MT that ensures adequate retention of crop residue is recommended with a resultant improvement in soil health.