Effect Of No-tillage On Soil Organic Carbon And Nitrogen And Their Pools In Rainfed Agriculture Of Northern China

The influence of different tillage practices on the changes of soil organic carbon and nitrogen ismore significant under long-term rather than short-term research. Despite the great interest on the effectof no-tillage (NT) management practice on carbon and nitrogen sequestration, the long-term effect ofNT practice on the soil organic carbon and nitrogen and their pools in Northern China virtually remainunclear. This paper includes two experimental sites with different experimental periods (Linfen17yearsand Shouyang7years). The First experimental site is Linfen, where we evaluated the long-term (after17years) effects of NT and conventional tillage (CT) practices on the soil organic carbon and nitrogenand their pools at different depths ranging from0-60cm using a cinnamon soil of Linfen city, Shanxi.Randomized block design with three replications were used to evaluate both the tillage and its effects onthe yield performance of winter wheat (Triticum aestivum L.).The results indicated that NT practice increased soil bulk density, soil organic carbon stock, soilorganic carbon (SOC), particulate organic matter–carbon (POM-C), dissolved organic carbon (DOC)and microbial biomass carbon (MBC) in the top layers ranging from0-10cm by8.5,84,56,111,83and177%, respectively. The contents of the SOC fractions linearly increased in line with the SOC.Moreover, the NT management practice increased soil total nitrogen (STN), soil total phosphorus (STP),particulate organic matter–nitrogen (POM-N), dissolved organic nitrogen (DON) and microbial biomassnitrogen (MBN) in the top layers (0-10cm) by63,14,141,57and326%, respectively. Furthermore,the yield from the winter wheat (Triticum aestivum L.) has increased by28.9%in NT practice ascompared with CT.In the second experimental site (Shouyang), the impact of tillage on soil organic carbon andnitrogen with their pools was studied over the maize growing stages in cinnamon soil of Northern China.Treatments consisted of NT and CT laid out in a randomized block design with three replications. SOCand SOC pools as well as soil organic nitrogen and its pools were measured four times, at differentdepth levels (0-60cm), over the year of2010growing season. Sampling periods were seeding (April27), jointing and flowering (June16), maturity (August10) and Harvesting stages (October8). Theresults indicated that NT showed higher performance and significance (P≤0.05) at jointing andflowering stage more probably due to sufficient moisture and temperature in the soil at this period. The NT practice increased SOC, POM-C, DOC and MBC content at jointing and flowering stage at the toplayers by43,24,62.5and66%, respectively compared to the same growing stage under CT treatment.The impact of tillage differences was seen more in STN and DON in this experimental site where NTshowed higher significance (P≤0.05) in the surface and subsurface layers (0-20cm). The NT treatmentincreased STN and DON by7.7and37.5%, respectively at jointing and flowering stage. However,maize yield under NT practice fluctuated and showed lower values. The Effect of time was of a greatmagnitude than those attributed to tillage treatments. This particular research illustrated that, measuringsoil quality based on soil organic carbon, nitrogen and microbial components must take into accountseasonal changes in soil physical and chemical conditions.Generally, the data shows that NT is effective and sustainable management practice to improvecarbon and nitrogen sequestration, soil quality and increase soil fertility for better crop yield withpositive environmental impacts in the rainfed dryland farming of Northern China.