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Little information is available about their influences of conservation tillage on the distribution and storage of soil organic C(SOC) and total N in soil profiles in the North China Plain.We investigated the changes in SOC and total N as related to the shift from conventional to conservation tillage using a long-term field experiment a with a winter wheat (Triticton aestivton L.)-corn (Zea mays L.) double cropping system.The experiment included four tillage treatments for winter wheat:moldboard plow without corn residue return (MP-R), moldboard plow with corn residue return (MP+R), rotary tillage (RT), and no-till (NT).Compared with the MP-R treatment, returning crop residue to the soil (MP+R, RT, and NT) increased SOC and total N in the 0-to 30-cm soil layer, but no distinct changes in SOC and total N concentration were observed among the four treatments at soil depths >30 cm.Compared with the MP+R treatment, the RT and NT treatments increased SOC and total N concentration significantly in the 0-to 10-cm layer but decreased SOC and total N concentration in the 10-to 20-cm layers.As a consequence, soil profile SOC and total N storage did not vary among the MP+R, RT, and NT treatments.Thus under the experimental conditions,conservation tillage (RT and NT) increased SOC and total N contents in the upper soil layers, but did not increase SOC and total N storage over conventional tillage (MP+R) in the soil profile.