Effects of long-term Chinese milk vetch application coupled with reduced chemical fertilizer usage on soil ammonium nitrogen adsorption and desorption characteristics
This study aimed to clarify the effects of the long-term application of reduced chemical fertilizers combined with Chinese milk vetch on the adsorption and desorption characteristics of ammonium nitrogen in soil.A 13-year long-term positioning test was conducted using five treatments:no fertilizer(CK),fertilizer only(CF),22500 kg/hm2 Chinese milk vetch+80%fertilizer(G+0.8CF),22500 kg/hm2 Chinese milk vetch+60%fertilizer(G+0.6CF),and 22500 kg/hm2 Chinese milk vetch+40%fertilizer(G+0.4CF).The ammonium nitrogen adsorption and desorption characteristics of soil subjected to different fertilization treatments were examined,and the relationship between soil ammonium nitrogen adsorption and desorption characteristic parameters and soil physicochemical properties was analyzed.The results showed that Langmuir's isotherm adsorption equation demonstrated a good fit with the adsorption characteristics of soil ammonium nitrogen(R2=0.9969-0.9979,P＜0.01).Compared with those in CK soil,the maximum adsorption amount and maximum buffering capacities of ammonium nitrogen in soil subjected to Chinese milk vetch+reduced fertilizer treatment decreased by 4.85%-13.46%and 4.55%-7.36%,respectively.The average desorption amount and desorption rate of soil ammonium nitrogen were in the following order:G+0.8CF＞G+0.6CF＞G+0.4CF＞CF＞CK.Compared with those of CK soil,the total nitrogen and available nitrogen concentrations of soil treated with Chinese milk vetch combined with reduced fertilizer increased by 19.42%-46.60%and 15.24%-25.88%,respectively.Correlation analyses revealed that the desorption rate had significantly positive correlations with soil total nitrogen and available nitrogen and a significantly negative correlation with soil pH.Redundancy analysis demonstrated that pH and available nitrogen were the main factors causing the differences in adsorption and desorption characteristic parameters of soil ammonium nitrogen,accounting for 56.7%and 39.1%of all variations,respectively(P＜0.05).In summary,long-term Chinese milk vetch application coupled with reduced chemical fertilizer usage reduced soil adsorption of ammonium nitrogen,increased soil desorption of ammonium nitrogen,reduced soil nitrogen fixation,and improved nitrogen availability.Considering the adsorption and desorption characteristics of soil ammonium nitrogen and soil nutrient content,treatments involving a chemical fertilizer reduction of 20%-40%combined with 22500 kg/hm2 of Chinese milk vetch were potentially suitable for the southern Henan rice area.
Chinese milk vetchsoil ammonium nitrogenadsorption and desorptioncharacteristic parameters
NETL
NSTL
万方数据
