Hedgerow ridge: A novel and improved method of ridge tillage to reduce water, sediment, and nutrient losses from sloping farmlands in Songhua River basin, northeast China

Abstract

Hedgerow ridge (HR) is a novel farming technique that consists of clover (Trifolium repens cv. Haifa.) hedgerows grown on short cross ridges that were established in furrows and running perpendicular and between longitudinal ridges. Additionally, the HRs and longitudinal ridges form pitting fields (PF). A three-year field experiment was conducted to investigate HR effects on reducing sediment, runoff, and soil nitrogen (N) and phosphorus (P) losses in a sloping farmland. There are eight treatments, which are traditional longitudinal ridge tillage (CK1); cross ridge tillage (CK2); HR + 1 m (H1PL [T1]), HR + 3 m (H3PL [T2]), and HR + 5 m (H5PL [T3]) length PF plus longitudinal ridge tillage; and short cross ridge (NHR) + 1 m (N1PL [T4]), NHR + 3 m (N3PL [T5]), and NHR + 5 m (N5PL [T6]) length PF plus longitudinal ridge tillage. The results indicate the following: (1) compared with CK1, the sediment and runoff of CK2 decreased 46.9% and 52.9%; H1PL, H3PL, and H5PL decreased sediment by 44.6%, 44.1%, and 42.1%; and decreased runoff by 50.1%, 49.8%, and 49.2%. N1PL, N3PL, and N5PL can also decrease water and soil losses in sloping farmland. Compared with H1PL, H3PL, and H5PL, N1PL, N3PL, and N5PL increased sediment by 16.3%, 12.6%, and 39.5% and increased runoff 29.6%, 46.8%, and 76.9%. HR technical effects on control sediment and runoff losses are close to CK2 and reach significant differences (P < 0.05). (2) Compared with CK1, total nitrogen (TN) concentration of sediment and TN concentration of runoff of all treatments were increased but total phosphorus (TP) concentration of sediment and TN concentration of runoff of all treatments were unchanged. Total N and TP concentration of all treatments were increased, and there are significant differences among treatments regarding TN concentration and no significant differences among treatments regarding TP concentration. Soil N from sloping farmland did not increase because contribution from runoff reduction is more than TN concentration of runoff increment.