Physical and chemical properties of high yield cinnamon soils and the main soil factors deciding maize yield in western Liaoning, China

Objectives Topsoil structure and fertility affect the growth and yield of maize. This paper studied the structure and fertility of topsoils under different maize yield levels, so as to clarify the important factors deciding yield, and provide a reference for the cultivation of fertile cinnamon soil in western Liaoning Province.

Methods 56 maize fields were selected and divided into 3 categories according to yield levels ( < 6000, 6000–9000 and > 9000 kg/hm²). Soil physical properties (topsoil and subsoil thickness, compaction, bulk density and porosity) and nutrient contents (organic matter, available N, available P and available K) were measured, and the maize root morphology was determined. The importance of the tested items was specified.

Results Maize yield increased with the increase of topsoil thickness, but opsite with the increase of subsoil thickness. The soil compaction, bulk density and soil porosity among different maize fields were not significantly different in soil layer of 0–10 cm, but significantly different in soil layer of 10 cm–subsoil. All the indexes of soil structure in fields with yield > 9000 kg/hm² were superior to those in fields with yield < 9000 kg/hm². Also, the dry weight and length of maize roots in fields with yield > 9000 kg/hm² were significantly higher than those in fields with yield < 9000 kg/hm². Maize roots in all fields were mainly distributed in 0–20 cm soil layer. In maize fields with yield < 6000, 6000–9000 and > 9000 kg/hm², the dry weight of roots in 0–20 cm soil layer were 83.3%, 79.8% and 81.1%, and the root lengths were 83.0%, 74.6% and 71.7% of the total in 0–40 cm soil layer, respectively. The water and nutrients absorbed by roots were thus mainly from 0–20 cm soil layer. In spite of that, the root distribution in 20–40 cm soil layer in fields with yield > 9000 kg/hm² were still significantly higher than those in fields with yields ranged from 6000 to 9000 kg/hm² and < 6000 kg/hm². According to analysis of predicting the importance of variables, the topsoil thickness and available P content were the top two important factors affecting the yield of maize in western Liaoning.

Conclusions For maize yield level of > 9000 kg/hm² in the tested area, the ideal physical properties of the topsoil are 23 cm in thickness, compaction (0–20 cm) lower than 1000 kPa, bulk density 1.27 g/cm³, with total porosity of 52.2%, capillary porosity of 33.5%, and aeration porosity of 18.7%; The good chemical properties are organic matter 14.8 g/kg, alkali hydrolyzed nitrogen 34.7 mg/kg, available phosphorus 21.2 mg/kg and available potassium 159.9 mg/kg, respectively. Increasing available P content and topsoil sickness are the top two targets for middle and low yield fields in the tested area.