TILLAGE TIME AFFECTS SOIL HYDRO-THERMAL PROPERTIES, SEEDLING GROWTH AND YIELD OF MAIZE (ZEA MAYS L.)

Two-year experiments were conducted to determine optimum tillage time to improve soil compaction and hydro-thermal properties for maize growth. Two tillage treatments: no-tillage (NT), and subsoiling (SS) were performed in correspondence to eight tillage times from March 25 to July 20 (I: March 25, II: April 10, III: April 25, IV: May 10, V: May 25, VI: June 10, VII: July 5, and VIII: July 20) at 15 days interval, synchronously with eight sowing times. SS significantly decreased soil bulk density (0-30 cm) by about 0.13 g cm(-3) at times of I-V, and about 0.08 g cm(-3) at VI-VIII. Increment in total soil porosity due to SS was about 3.88% during I-V and about 2.27% at VI-VIII. SS significantly increased soil moisture content by 1.60% in 10-30 cm soil profile. Soil minimum temperature significantly increased by about 0.58 degrees C (0-20 cm) for I-V, while an increase of 1.06 degrees C (0-10 cm) was seen for maximum soil temperature due to SS. Greater seedling dry matter coupled with higher growth, and yield improvement was achieved with SS. Dry matter accumulation and grain yield was maximum for May 25 to June 10 sowing as compared to early (22%, 43.5%) and late (60%, 41%, respectively) sowing due to SS versus NT. Initial SS intervals could alleviate soil compaction and low temperature stress for spring maize, with improved soil hydrothermal properties.