Effect Of Brachiaria Grass Planting On N₂O Emission From Lateritic Soils In Tropical Regions

Nitrous Oxide(N2O)is not only an important greenhouse gas,ozone in the stratosphere and can react and destroy the ozone layer.The retention time of N2O in the atmosphere is long,and the concentration increases continuously.More and more attention has been paid to the emission reduction of N2O.The farmland ecosystem is an important source of N20.Inhibition of N nitrification can reduce the production of N2O to a certain extent.Screening and application of plant source inhibitors is the current and future research hot spot of nitrogen fertilizer inhibitors.Brachiaria native to African savanna can inhibit nitrification to some extent.However,the effect of brachiaria on soil nitrogen transformation and N20 emissions has not been reported.In this experiment,the African humidogene Brachiaria as the research object based on local eremochloa ophiuroides.The effects of brachiaria grass on nitrification and N2O emission of N were studied by field experiment and indoor culture test.In the field experiment,2 varieties and 4 nitrogen levels were set up,with 8 treatments,and the amount of nitrogen was 0,150,225 and 300 kg ha-1,respectively.There are two test indoor cultivation,the grass straw test,2 varieties of 3 x amount of straw,to add straw as control,In 7 treatments,the amount of 3 straw added was 1%,2%and 3%of the dry soil weight,respectively,the amount of nitrogen fertilizer was 150 mg · kg-1;second for the root soil culture experiment,test soil for arm root soil,Centipedegrass and grass soil soil system,each kind of soil with and without nitrogen addition treatment,A total of 6 processes,nitrogen content was 100 mg · kg-1.The results of the experiment are as follows.1.The cumulative annual N2O emissions of brachiaria grass and centipede grass increased with the increase of nitrogen application rate.Under the same nitrogen application rate,the cumulative N2O emissions of brachiaria grass soil were significantly higher than those of planting centipede grass.Compared with the root soil of the centipede grass,The root soil of brachiaria grass has a stronger nitrification inhibition effect,After applying nitrogen fertilizer into the soil,The cumulative emission of N20 41.69 ug N2O-N · kg-1 in the soil of the brachiaria grass root system,The cumulative emission of N2O 129.23 ug N2O-N ·kg-1 in the soil of the eremochloa ophiuroides root system,There is a significant difference between the two.Brachiaria grass straw and eremochloa ophiuroides straw increase N20 emission in soil.The more the amount of brachiaria grass straw added,the greater the cumulative emission of N2O.The cumulative N2O emission of the eremochloa ophiuroides straw increased first and then decreased with the increase of the amount of the false eremochloa ophiuroides straw added.2.Under the same nitrogen application level,the cumulative emission of the unit biomass N2O of brachiaria grass was lower than that of the pseudo thrifty.From the unit biomass evaluation,the brachiaria grass has the effect of inhibiting N2O emission compared with the eremochloa ophiuroides.3.N2O emission from brachiaria grass is positively correlated with soil pore water content.N20 emission from eremochloa ophiuroides is positively correlated with soil temperature,soil ammonium nitrogen and nitrate nitrogen.4.Brachial grass planting can inhibit nitrification,The suppressing substance possible be derived from the root of brachial grass.