| A proper stubble height plays a significant role in the regeneration of plant communities and the circulate accumulation of pasturage nutrient,and a proper stubble height of defoliation also influences the economic yield,nutrient content and nutrient storage of harvested pasturage.The stubble height of defoliation directly influences the economic yields of pasturage.An extremely high stubble height leads to less economic yields of pasturage and affected nutrient value and digestibility of pasturage.An extremely low stubble height of defoliation leads to high economic yields of pasturage,but bad impacts will appear,such as plant regeneration,the economic yields of pasturage,circulate nutrient,litter yields,and the supply capability of soil nutrient,resulting in the degradation of grasslands caused by imbalanced nutrient.Therefore,studying the yield dynamics,nutrient contents dynamics and nutrient storage of pasturage and ensuring the proper stubble height of cutting grassland are providing significant theoretical and economic values for reasonably utilizing natural cutting grasslands.This study arrived at following conclusions:1.During stubble procession in five years,the economic yields of pasturage have reduced with the increased stubble height,and the drop of the economic yields of each stubble procession with the increasing year of defoliation alleviated.Except H0,the differences between products yields of other stubble processions,the harvested product yields are convergent.2.The stubble higher than 10 cm is beneficial to the accumulation of above-ground biomass.In terms of population,less than 6cm of stubble is conducive to the accumulation of biomass on the sheep meadow,and stubble above 6cm is conducive to the accumulation of above-ground biomass of Stipa krylovii,14 cm of stubble remaining,favoring other populations on the ground accumulation of biomass.3.The height of Chinese leymus reduced in 6cm stubble height during the early period of defoliation and rose with the increasing defoliation years.The stubble height higher,the drop of Chinese leymus smaller.With the increasing height of stubble,the economic yields of Chinese leymus decreased.The stubble higher than 10 cm is beneficial forthe rising of Stipa krylovii capillate heights.The stubble height higher,the drop of Stipa krylovii smaller.The stubble between 0cm-12 cm of defoliation leads to the stepped reduction of Stipa krylovii capillate yields.4.The storage of various elements of Chinese leymus and Stipa krylovii is affected by element storage and harvested yields of Chinese leymus and Stipa krylovii.The storage of C and N are mainly affected by yields,and the extent that P storage is affected by yields is weaker than that of C and N.The stubble procession can increase the content of N in compounds,and the content of P increases in H0 and H6,and reduces in other stubble processions.The storage of C,N and P compounds reduce with the increasing stubble height.5.The stubble height higher,the organic content of soil layers between in 0-20 cm less.Stubble processions have small impacts on the organic content of soil layer below 20 cm.The procession of H0 and H6 mainly affect the organic content of soil layer between 0-10 cm,the procession of H8-H12 mainly affects the organic content of soil layer between 10-20 cm,and the each procession has small impacts on the organic content of soil layers between 20-30 cm.6.Hi-duty defoliation(H0)reduces N content of soil in soil layers between 0-20 cm and increases the quick-acting N.Properly increasing stubble heights of defoliation is beneficial to accumulate N of soil in deepsoil layers.7.Different stubble processions reduce total P and quick-acting P content of soil in soil layer between 0-10 cm,properly increasing the stubble heights of defoliation is beneficial to accumulate entire P in soil layers between 20-30 cm and keep the quick-acting phosphorus in soil layers between 10-30 cm. |
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