EFFECT OF CHANGES IN PRODUCTION MODE ON NITROGEN AND PHOSPHORUS BALANCE IN YUNNAN HANI TERRACED SYSTEM
This research aims to investigate the impact of long-term changes in production modes on the material flow patterns in terrace systems,so as to establish a scientific basis for preserving Hani terraced fields,promote sustainable development and ecological resources utilization in the Hani region,and achieve sustainable use in Hani terraced fields.To accomplish the purposes of this study,the Net Anthropogenic Nitrogen/Phosphorus Inputs model(NANI/NAPI)was used to calculate NANI and NAPI values and their relevant components during two different development periods in Yuanyang county,from 1985 to 1986 and from 2009 to 2020.The overall trend of NANI and NAPI in Yuanyang county showed an initial increase followed by a decrease.In 1985,NANI and NAPI were 2914 kg/(km2·a)and 249 kg/(km2·a),respectively.Both reached their highest values in 2016,with values of 9 860 kg/(km2·a)and 685 kg/(km2·a),respectively,followed by a downward trend.The NANI comprised four components,each of which contributed to the overall NANI in the following ranges:food/feed net nitrogen input(20%to 45%),atmospheric nitrogen deposition(12%to 40%),crop nitrogen fixation(6%to 12%),and fertilizer nitrogen input(5%to 52%).The NAPI included three components,with food/feed net P(phosphorus)input accounting for 3%to 50%of the total NAPI.The contribution of P fertilizer application and non-food P application to the total NAPI was 32%～57%and 19%～41%,respectively.There was an observable stepwise change in the NANI/NAPI ratio in Yuanyang county,with NANI/NAPI ratios of 11.7 and 11.0 in 1985 and 1986,respectively.The NANI/NAPI ratios remained unvarying at approximately 18.5～18.8 from 2018 to 2020.Based on the correlation between NANI,NAPI,and their components,it was found that the R2 value between NANI and food/feed nitrogen input was 0.81(P<0.01),which was same as the R2 value between NANI and fertilizer nitrogen input.Similarly,the R2 value between NAPI and food/feed phosphorus input was 0.90(P<0.01),while the R2 value between NAPI and fertilizer phosphorus input was 0.59(P<0.01).In summary,the trend of NAPI exhibited a strong correlation with NANI in Yuanyang county,showing a distinct stepwise pattern of initial increase followed by a subsequent decrease.This trend is consistent with the shift in local production modes.
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