Effects of Subsoiling Tillage on Soil Properties, Maize Root Distribution, and Grain Yield on Mollisols of Northeastern China

Soil compaction creates unfavorable soil physical and nutrient conditions, restrains root penetration and distribution, and reduces crop yield. A field experiment was established to assess the effects of tillage treatments on soil properties, root distribution, and grain yield of maize (Zea mays L.) on some Mollisols of Northeastern China. The two treatments included in rotary tillage (RT) and subsoiling tillage (ST). The results showed that soil bulk density, penetration resistance, soil moisture, available nitrogen content, root distribution of maize, and grain yield were significantly affected by tillage systems. Compared with RT, ST had lower soil bulk density and penetration resistance, but greater soil moisture and available nitrogen contents, especially in subsoil layer (i.e., 15- to 45- cm). The ST practice significantly increased the average root length density by 13.0% than that of RT mainly due to better vertical and horizontal distribution between the rows. Average grain yield and dry matter weight of maize increased by 693 kg ha(-1) (6.3%) and 933 kg ha(-1) (3.7%), respectively, under ST compared with those under RT. These data show that subsoiling tillage can loosen the soil, fracture the plow pan, increase the availability and infiltration of soil moisture and nitrogen in subsoil layers, improve the vertical and horizontal extension of maize root system in the soil, and increase grain yield on Mollisols of Northeastern China.