Effects of different irrigation quantity on migration of soil nitrate nitrogen and growth of pear

To guide the reasonable irrigation for the pear producing area in southern Hebei Province and reduce the soil nitrate nitrogen leaching, the soil water content, soil nitrate nitrogen vertical transport and the growths of pear were studied in the Huangguan-pear orchard by using the randomized block experiment design. Three treatments were considered: little irrigation (LI), medium irrigation (MI), and flood irrigation (FI) used as the control. The results showed that the LI treatment (112.5 mm water quantity) can significantly decrease the single fruit weight, yield per plant and soluble solid content, and retain 81.73% relative absorbing roots of pear to distribute in 0 to 60 cm deep soil. And the MI treatment (225 mm water quantity) can completely infiltrate the soil within 90 cm, retain the relative absorbing roots and soil nitrate nitrogen to more uniformly distribute in 0 to 90 cm deep soil, and guarantee the yield and fruit quality of pear. Moreover, the FI treatment (337.5 mm water quantity) can retain 52.63% relative absorbing roots of pear to distribute in 70 to 100 cm deep soil, and make the soil nitrate nitrogen down to 60 to 90 cm deep soil which will increase the risk of soil nitrate nitrogen leaching. As a result, the MI treatment is a more suitable irrigation quantity for pear orchards in southern Hebei Province of China.