[Soil Respiration in Response to Different Ridge/Furrow Ratios and Its Relationship with Soil Moisture and Temperature Under Ridge-Furrow Planting Patterns].

This study aimed to explore soil respiration in response to soil moisture and soil temperature subjected to different ridge/furrow ratios under various planting patterns. Traditional flat planting and three different ridge-furrow plantings with altering ridge/furrow ratios, i. e. 20:40 cm (P40); 30:30 cm (P30); 40:20 cm (P20), were performed in the present study. Soil respirations among different planting patterns were compared. Their relationships with soil moisture and soil temperature were also analyzed. The results showed that soil respiration flux of four planting patterns reached its minimum value during the wintering stage, started to rise during the returning green stage until it reached a peak value at the flowering stage, and decreased gradually when reaching the maturity stage. The magnitude of soil respiration flux in three ridge-furrow planting patterns followed this order: P40 > P30 > P20, which implied that increasing ridge width could improve soil respiration by 1.2%-18.4%. In addition, soil respiration fluxes of three ridge-furrow plantings patterns were significantly higher than those under conditional patterns during the seedling stage (P<0.05). The soil temperature of ridge-furrow planting patterns was higher than that of the conditional flat pattern from the seeding stage to the wintering stage, but was converse from the jointing stage to the maturity stage. Moreover, three ridge-furrow planting patterns have shown significant effect on preserving soil water storage in comparison with the conditional flat pattern. In general, increasing the width of the ridge increased soil water storage due to less rainfall from the seedling stage to the jointing stage. The correlation analysis indicated a positive and significant correlation coefficient between soil respiration and soil temperature (P<0.01). Correlation coefficients in case of P40 and P30 were higher than those in P20 and the conditional flat pattern. The quadratic model of two-factor soil moisture and soil temperature could explain 61.7%-74.1% of variations in soil respiration. The single factor of the soil temperature model could explain 50.3%-68.2% of variations in soil respiration. Those results could provide a theory basis for further evaluation of ecological effect on the ridge-furrow planting patterns.

[Effects of Tillage on Soil Respiration and Root Respiration Under Rain-Fed Summer Corn Field].

To explore the effects of different tillage systems on soil respiration and root respiration under rain-fed condition. Based on a short-term experiment, this paper investigated soil respiration in summer corn growth season under four tillage treatments including subsoiling tillage (ST), no tillage (NT), rotary tillage (RT) and moldboard plow tillage (CT). The contribution of root respiration using root exclusion method was also discussed. The results showed that soil respiration rate presented a single peak trend under four tillage methods during the summer corn growing season, and the maximum value was recorded at the heading stage. The trends of soil respiration were as follows: heading stage > flowering stage > grain filling stage > maturity stage > jointing stage > seedling stage. The trends of soil respiration under different tillage systems were as follows: CT > ST > RT > NT. There was a significant correlation between soil respiration rate and soil temperatures (P < 0.05), which could explain 35%-75% variability of soil respiration using exponential function equation. However, there was no significant correlation between soil respiration rate and soil moisture. Root respiration accounted for 45.13%-56.86% of the proportion of soil respiratio n with the mean value 51.72% during the summer corn growing season under different tillage systems. Therefore, root exclusion method could be used to study the contribution of crop growth to carbon emission, to compare effects of different tillage systems on the contribution of root respiration provides the bases for selecting the measures to slow down the decomposition of soil carbon.

[Effects of tillage mode on water use efficiency and yield of summer maize under different simulated rainfalls].

Based on the tillage practices of summer maize and the rainfall pattern in Northwest China, and by using self-made simulated rainfall device, a field experiment was conducted on the effects of plowing, no-tillage, and no-tillage plus mulching on the water use efficiency (WUE) and yield of summer maize under rainfalls 250, 350 and 450 mm from June to September, 2010. Compared with plowing, no-tillage increased the WUE and yield under rainfall 250 mm by 26% and 16.5% and under rainfall 350 mm by 17.6% and 6.1%, respectively. Under rainfall 450 mm, the water storage was smaller in treatment no-tillage than in treatment plowing, and the WUE and yield in treatment no-tillage were 1.1% and 0.6% lower than those in treatment plowing, respectively. No-tillage plus mulching overcame the disadvantage of no-tillage in lesser water-storing under sufficient rainfall than plowing. Under the three rainfalls, no-tillage plus mulching could effectively inhibit the soil evaporation between plants, decrease the invalid water consumption of bare soil, and increase the soil water storage and the rate of evapotranspiration to water consumption. Compared with plowing, no-tillage plus mulching increased the WUE and yield under rainfall 250 mm by 48.6% and 32.9%, under rainfall 350 mm by 51.6% and 27.1%, and under 450 mm rainfall by 23.7% and 13.1%, respectively. In sum, relative to plowing, no-tillage showed its superiority in increasing WUE and yield under rainfalls 250 and 350 mm, whereas no-tillage plus mulching increased the WUE and yield significantly under rainfalls 250 and 450 mm.

[Effects of tillage and mulching on orchard soil moisture content and temperature in Loess Plateau].

A field experiment was conducted to study the effects of different tillage system (no-tillage, rotary tillage, and plow tillage) and mulching (straw mulch, sod mulch, and film mulch) on the orchard soil moisture content and temperature in Loess Plateau. Under different tillage system, the soil moisture content in 0-1 m layer differed significantly in May, with the sequence of no-tillage (14.28%) > rotary tillage (14.13%) > plow tillage (13.57%), but had less difference in September. Straw mulch induced significantly higher soil moisture content than sod mulch, film mulch, and no-mulch. Among the treatments tillage plus mulching, no-tillage plus straw mulch resulted in the greatest soil water storage. The average soil temperature at daytime was in order of film mulch > no-mulch > sod mulch > straw mulch, and the change range of soil temperature was no-mulch > film mulch > sod mulch > straw mulch. Soil water storage under different mulching treatments was not always negatively correlated with soil temperature, but depended on the water conservation effect and heat-preserved capacity of mulching material. Above all, the main conservation tillage system for the orchards in Loess Plateau would be no tillage plus straw mulch.