| Weibei highland is located in Southern Plateau of China, where belongs to sub- humid area and a typical rainfed agricultural area. The area is an important grain production base in Shaanxi Province, meanwhile, spring maize is one of the main crop after the winter wheat.Due to the lack of water, the dry climate, loose soil, lack of fertility, serious soil erosion,which resulted in lower level of agricultural production. To explore the effects of soil water conservation, soil fertility, grain yield and economic increasing of different rotational tillage practices in spring maize field in Weibei highland, a field experiments of 3 kings of fertilizer level(balanced fertilization, conventional fertilization, and low fertilization treatment) and straw mulching or returning NT/ST(no-tillage in the first year, subsoiling in the second year, again no-tillage followed by alternating the next year), ST/CT(subsoiling in the first year, conventional tillage in the second year, again subsoiling followed by alternating the next year) and CT/NT(conventional tillage in the first year, no-tillage in the second year,again conventional tillage followed by alternating the next year) rotational tillage,and conventional tillage(CT/CT), continuous subsoiling(ST/ST)and continuous no-tillage(NT/NT) treatments were conducted during 2007—2015 in Heyang, Shaanxi Province. Soil physical and chemical properties, soil moisture characteristics were measured to analyzed maize agronomic traits and yield effects. The main results are as follows:1. Effects of tillage practices on soil bulk density and soil porosityThree rotational tillage practices were conductived to decreased topsoil soil bulk density,and increased soil total porosity. The NT/ST treatment decreased average soil bulk density by10.6% and increased soil porosity by 10.6%than pretreatment, decreased soil bulk density by9.4% and enhanced soil porosity by 9.6% than CT/CT treatment. NT/ST, ST/CT and ST/ST treatments had higher water stable aggregates and mechanical stable aggregate content(R0.25)than CT/CT treatment at 0—40 cm.2. Effects of tillage practices on soil soil moisture storageIn the seven fallow of eight years experimental, average soil water storage at 0—200 cm under NT/ST, ST/CT, CT/NT, NT/NT and ST/ST treatment was 5.8, 1.3, 1.7, 1.4 and 0.3percentage higher than CT/CT treatment. The NT/ST and CT/NT treatments had certainadvantages on storage rainwater in wet years, NT/ST and NT/NT had better effects in impounding water in normal years, and NT/ST and CT/NT had high water efficiency in dry years. And the NT/ST, ST/CT, CT/NT, NT/NT and ST/ST treatments increased average soil water storage at 0—200 cm of growth stage by 7.5 mm, 3.8 mm, 4.8 mm, 9.5 mm and 4.6 mm in comparison to CT/CT treatment, of which the NT/ST treatment was the most obvious.3. Effects of different tillage practices on soil fertilityCompared to low fertilization and conventional fertilization, balance fertilization was more conducive to increased soil organic matter and and soil nitrogen, phosphorus and potassium accumulation. Compared with CT/CT, NT/ST, ST/CT and CT/NT rotational tillage practices were beneficial to the accumulation of soil organic matter, average soil organic matter under three rotational tillage practices treatment was 3.7%, 2.5% and 5.7% higher than CT/CT theatment. Simultaneously, the NT/ST treatment in favor of increasing soil total potassium content.4. Effects of different tillage practices on maize agronomic traitsAverage biomass of the harvest ranked as balanced fertilization> low fertilization >conventional fertilization. Chlorophyll content, net photosynthetic rate and transpiration rate under conventional fertilization were the highest, followed by balanced fertilization, low fertilization was the worst. NT/ST and ST/ST treatments showed higher biomass in harvest,but grain yield under NT/ST trteatment was the highest. Net photosynthetic rate under the three rotational tillage practices shoued the highest value, transpiration rate under ST/CT and CT/NT showed higher value and chlorophyll content under ST/CT and ST/ST treatments shoued the highest value.5. Effects of different tillage practices on maize grain yield, WUE, RUE and economic benefitCompared with low fertilization and balance fertilization, conventional fertilization is more conducive to increased grains per spike and harvest index, while balanced fertilization tended to increase 1000-kernel weight and grain yield. Average grain yield of eight years expressed as NT/ST >ST/ST>ST/CT>CT/NT>NT/NT>CT/CT, the NT/ST treatment had the highest grain yield and WUE, increased grain yield by 6.0%-18.7% and 9.0%-16.8%compared to other treatments, respectively. The grain yield under NT/ST and NT/NT was the highest in wet years, under followed by normal years and dry years. The grain yield and WUE under NT/ST and NT/NT was the highest in wet years, the grain yield under NT/ST and ST/CT had the higher value in normal years, but WUE under NT/ST was the highest in normal years, the NT/ST and ST/ST treatments had higher grain yield and NT/ST and NT/NT had higher WUE in dry years. In the three fertilization level, the blanced fertilization hadhigher NUE and economic benefits, followed by conventional fertilizationg and low fertilization. The NT/ST had higher WUE and economic benefit, and the CT/NT had higher RUE value. |
PDF Full Text Request