Paddy Soil Respiration And Organic Carbon Fractions Under Wide Ridge Cultivated With No-tillage In Central China

Study the effect of wide ridge cultivated paddy field on soil respiration and organic carbon fractions in no-tillage paddy soils in central China, to assess the no-tillage with ditch paddy soil carbon and organic carbon accumulation provide scientific reference, and provide technical support for no-tillage technology promotion.Based in central China Rapeseed- Rice(Rapeseed- Middle Rice) system testing ground, by design 0.6 m(W1), 1.2 m(W2), 1.8 m(W3) and 2.5 m(W4) four different widths of no-tillage wide ridge paddy and flat no-tillage paddy(FNT) and flat as tillage(T) paddy, monitoring the soil respiration and it’s component(total respiration, heterotrophic respiration) temporal and spatial variation characteristics, and the change characteristic of soil active organic carbon fractions(microbial biomass carbon, dissolved organic carbon, easily oxidizable carbon, total organic carbon and soil aggregate carbon) also were researched.(1) Each treatment center or edge of wide ridge accumulated temperature and canopy light transmittance rate was not significantly different; no-tillage with ditch main impact of accumulated temperature and canopy light transmittance distribution in space, the accumulated temperature of edge of wide ridge significantly higher center, and middle and bottom of canopy light transmittance of edge of wide ridge significantly higher center among them.(2) Diurnal variation of the no-tillage wide ridge paddy soil respiration(tillering stage and full heading) feature analysis shows, diurnal variation of soil respiration fluxes present different law in two main growth period: At tillering stage, each wide ridge treatment CO2 fluxes of the edge of and center peaked at 18:00; At full heading, only the center of wide ridge treatment CO2 fluxes peaked at 18:00, the edge of wide ridge CO2 fluxes no obvious peak,but the day soil respiration was significantly higher than during at night. Further studies suggested that 9: 00-12: 00 is the best time to monitor the diurnal variation of soil respiration.(3) Studied the seasonal changes in the no-tillage wide ridge paddy soil respiration and it’s components, showed that soil total respiration and heterotrophic respiration has obvious seasonal variation, each treatment center or edge of wide ridge both soil total respiration and heterotrophic respiration peaked at tillering stage and full heading.(4) Analysis of the spatial variance of the no-tillage wide ridge paddy soil respiration and it’s components pointed out, because the no-tillage wide ridge ridgeditch special configuration, cause the edge relative to the marginal loss of fertilizer large center, nutrient absorption and utilization of rice were reduced in the edge of wide ridge, rice root biomass and above ground biomass was significantly lower, thereby reducing soil respiration and it’s components, therefore wide ridge no-tillage paddy soil respiration and it’s components were significantly lower at the edge than at center.(5) Analysis of the no-tillage wide ridge paddy soil carbon components show, wide ridge treatments dissolved organic carbon contents were significantly higher at the edge than at center; the microbial biomass carbon and quotient of microbial biomass carbon were significantly less at the edge of wide ridge than at center, and were least in 1.8 m wide ridge treatment; the total organic carbon contents were significantly higher in the wide ridge treatments than both in FNT and T, and were significantly lower in the edge of the wide ridge than in the center’s; the 1-0.25 mm and 0.25-0.053 mm fraction aggregates carbon content of the edge of the wide ridge as well as 2-1 mm and 1-0.25 mm fraction of the center of the wide ridge were largest in 1.8 m treatment; the carbon pools management index was significantly greater in four wide ridge treatment than both in FNT and T.(6) Comprehensive analysis of the no-tillage wide ridge paddy soil cumulative CO2 emissions and yield showed, relative to T treatment, no-tillage wide ridge and FNT treatment significantly reduced the cumulative CO2 emissions from paddy soil; 1.8 m treatment has minimum cumulative CO2 emissions from paddy soil, significantly lower than the T treatment with 18.5%-35.2%. Meanwhile, the yield analysis showed that, due to has the highest effective ear, 1.8 m treatment has the highest yield; comprehensive analysis of the yield and cumulative soil CO2 emissions indicate 1.8 m treatment has minimum CO2 emissions per unit of production, therefore it is a lower CO2 emissions and higher rice yield no-till rice technology.