Hongwen Li

Effects of 15 years of conservation tillage on soil structure and productivity of wheat cultivation in northern China

An understanding of long-term tillage and straw management impact on soil structure and productivity is necessary for the further development of conservation tillage practice in dryland farming areas. Data from a 15-year field experiment conducted in Shanxi, on the loess plateau of northern China, were used to compare the long-term effects of no-till and residue cover (NTSC) with conventional tillage (CT) in a winter wheat (Triticum aestivum L.) monoculture. Long-term CT and straw removal resulted in poor soil structure and low productivity. Mean soil bulk density in NTSC was 1.5% less than in CT and capillary porosity ( 2 mm was much greater for NTSC in the 0–0.20 m profile. Soil organic matter and total N and P were 27.9%, 25.6%, and 4.4% greater in NTSC, respectively, and earthworms (19/m2) were found only in the no tillage treatment. Crop yield and water use efficiency tended to be higher under NTSC than under CT, especially in the years of low rainfall, suggesting that the change in soil structure has provided a better environment for crop development. Our 15-year experimental data indicate that NTSC is a more sustainable farming system, which can improve soil structure, and increase productivity with positive environmental impacts in the rainfed dryland farming areas of northern China.

Effect of ridge tillage, no-tillage, and conventional tillage on soil temperature, water use, and crop performance in cold and semi-arid areas in Northeast China

In cold and semi-arid Northeast China, insufficient soil accumulative temperature and low water use efficiency (WUE) are the limiting factors for the further development of agriculture. Ridge tillage (RT) has been proposed to improve soil temperature and water conservation. Data from a 3-year field experiment conducted at two locations (Sujiatun and Lanxi) in Northeast China were used to compare RT, no-tillage (NT), and conventional tillage (CT) in a spring maize cropping system. At both sites, RT and NT significantly (P < 0.05) increased mean soil temperature to 0.10 m depth, relative to CT, by 0.7–2.4°C in the cold season during the spring maize growing stage. Mean soil moisture depletion in the RT treatment was greater by 1.2–4.1% (Sujiatun) and 0.6–3.0% (Lanxi) than in NT and CT, respectively. Mean maize yields over 3 years for RT were ~9.9% greater than for CT, whereas the yield advantage in the NT treatment was only slight. In Sujiatun, WUE was 8.0% and 8.6% greater under RT than under NT and CT, respectively, and in Lanxi, WUE was 7.7% and 9.6% greater under RT than NT and CT. Ridge tillage is recommended to the farmers to obtain higher crop yield and WUE in Northeast China.

Traffic and tillage effects on wheat production on the Loess Plateau of China: 1. Crop yield and SOM

Challenges for dryland farming on the Loess Plateau of China are continuous nutrient loss, low soil organic matter and crop yield, and soil degradation. Controlled traffic, combined with zero or minimum tillage and residue cover, has been proposed to improve soil structure and crop yield. From 1998 to 2006, we conducted a field experiment comparing soil organic matter and wheat productivity between controlled traffic and conventional tillage farming systems. The field experiment was conducted using 2 controlled traffic treatments (zero tillage with residue cover and no compaction, shallow tillage with residue cover and no compaction) and a conventional tillage treatment. Results showed that controlled traffic treatments significantly increased soil organic matter and microbial biomass in the 0–0.30 m soil profile. Controlled traffic with zero tillage significantly increased total N in the 0–0.05 m soil profile. The mean yield over 8 years of controlled traffic treatments was >10% greater than that of conventional tillage. Controlled traffic farming appears to be a solution to the cropping problems faced on the Loess Plateau of China.

Soil structure and crop performance after 10 years of controlled traffic and traditional tillage cropping in the dryland Loess Plateau in China

Soil degradation and the accompanying decline in crop yields are the main limiting factors for the further development of agriculture on the Chinese Loess Plateau. A 10-year experiment was conducted in Linfen on the Loess Plateau to assess the potential benefits of controlled traffic on agricultural production. In this region, long-term traditional ploughing with straw removal has resulted in a decline of soil productivity and poor soil structure. Several treatments were compared: controlled traffic with no-tillage and straw cover (NTSC), controlled traffic with shallow tillage and straw cover, and traditional tillage (TT) in a winter wheat (Triticum aestivum L.) monoculture. Results show clear benefits of controlled traffic farming. Winter wheat growth in ploughed plots was much slower than in controlled traffic plots. Mean yield from 1998 to 2007 was 11.2% lower for traditional tillage than for controlled traffic plots. The best results were achieved by a no-tillage straw cover and controlled traffic system (NTSC), which resulted in the greatest benefits to soil structure after 10 years. The NTSC significantly improved soil organic matter content in the top 30 cm by 27.2%, total N by 10.8%, and available P (top 10 cm) by 92.3% compared with TT. Aeration (>60 &mgr;m) and capillary porosity (2-60 &mgr;m) were 155.0% and 16.1% greater, respectively, in NTSC plots than in TT plots. Consequently, for NTSC, final water infiltration rates were 67.4% greater than for TT, whereas water content in the top 130 cm was 14.9% higher than in TT, respectively. We conclude therefore that controlled traffic combined with no-tillage and straw cover is a valuable system for restoring soil productivity and quality of seriously degraded soils on the Loess Plateau for the sustainable development of agriculture in dryland China.

Influence of conservation tillage practices on soil properties and crop yields for maize and wheat cultivation in Beijing, China

Conservation tillage is becoming increasingly attractive to farmers because it involves lower production costs than does conventional tillage. The long-term effects of sub-soiling tillage (ST), no tillage (NT), and conventional tillage (CT) on soil properties and crop yields were investigated over an 8-year period (2000–07). The study was conducted in a 2-crop-a-year region (Daxing) and a 1-crop-a-year region (Changping) of the Beijing area in China. At 0–0.30 m soil depth, water stability of macro-aggregates (>0.25 mm) was much greater for ST (22.1%) and NT (12.0%) than for CT in Daxing, and the improvements in Changping were 18.9% and 9.5%, respectively. ST and NT significantly (P   CT at both sites. Consequently, crop yields in ST and NT plots were higher than in CT plots due to improved soil physical and chemical properties. Within the conservation tillage treatments, despite similar economic benefit, the effects on crop yields for ST were better than for NT. Mean (2000–07) crop yields for ST were 0.2% and 1.5% higher than for NT at Daxing and Changping, respectively. We therefore conclude that ST is the most suitable conservation tillage practice for annual 2-crop-a-year and 1-crop-a-year regions in the Beijing area.

Traffic and tillage effects on runoff and soil loss on the Loess Plateau of northern China

This paper reports the outcome of 5 years of field plot runoff monitoring, 2 years of water erosion measurement, and a rainfall simulation experiment on moderately sloping farmland on the loess plateau of north-west China. The objective was to test different conservation tillage systems compared with the control treatment, conventional mouldboard plough practice (CK). Tillage, residue cover, and compaction effects were assessed in terms of runoff and soil erosion. Results from the runoff plots showed that conservation tillage, with more residue cover, less compaction, and less soil disturbance, could substantially reduce runoff and soil erosion compared with the control. No tillage with residue cover and no compaction produced the least runoff and soil erosion. Compared with the control, it reduced runoff and soil erosion by about 40% and 80%, respectively. At the start of the experiment, residue cover appeared to be the most important factor affecting soil and water conservation, particularly when antecedent soil moisture was limited. With the accumulation of tractor wheeling effects over the course of the experiment, soil compaction appeared to become a more important factor affecting runoff. Rainfall simulation was then used to assess the effect of non-inverting surface tillage and different levels of residue cover and wheel compaction on infiltration and runoff. This confirmed that wheel compaction effects could be greater than those of tillage and residue cover, at least under the 82.5 mm/h rainfall rate produced by the simulator. The wheeling effect was particularly large when the treatment was applied to wet soil, and severe even after wheeling by small tractors.

Spring wheat performance and water use efficiency on permanent raised beds in arid northwest China

Permanent raised beds have been proposed as a more productive and water-efficient alternative to the conventional system of flat, flood-irrigated bays for planting narrow-spaced crops in arid north-west China. Data from a field experiment (2005–2007) conducted in the Hexi Corridor at Zhangye, Gansu Province, China, were used to compared the effects of traditional tillage (TT), zero tillage (ZT), and permanent raised beds (PRB) on crop growth, yield, and water use in a spring wheat monoculture. The results show that PRB significantly (P < 0.05) increased soil water content to 0.30 m depth by 7.2–10.7% and soil temperature to 0.05 m depth by 0.2–0.9°C during the wheat-growing period relative to TT and ZT treatments. Bulk density in 0–0.10 m soil layer under PRB was also 5.8% less than for flat planting treatments. Mean wheat yields over 3 years on PRB plots were slightly greater and furrow irrigation in permanent beds was particularly effective in increasing irrigation water use efficiency (~18%), compared with TT and ZT treatments. This increase in water use efficiency is of considerable importance for these arid areas where irrigation water resources are scarce.

Traffic and tillage effects on wheat production on the Loess Plateau of China: 2. Soil physical properties

Controlled traffic zero and minimum tillage management with residue cover has been proposed as a solution to erosion and other soil degradation challenges to the sustainability of dryland farming on the Loess Plateau of China. This was assessed between 1998 and 2007 in a field experiment involving a conventional tillage treatment, and 2 controlled traffic treatments, no tillage and shallow tillage, with full straw cover in both cases. This paper reports the soil physical properties after 9 years of dryland wheat production under these treatments, and the substantial improvements seen in soils under controlled traffic. Compared with conventional tillage, controlled traffic significantly reduced soil bulk density in the 0–0.15 m soil layer, and increased total porosity in the 0–0.60 m soil layer, where macroporosity (>60 µm) and mesoporosity (0.2–60 µm) increased at the expense of microporosity (<0.2 µm). Readily available water content and saturated hydraulic conductivity were greater in controlled traffic treatments. Controlled traffic farming appears to be an improvement on current farming systems on the Loess Plateau, and valuable for the sustainable development agriculture in this region.

The adoption of conservation tillage in China

Conservation tillage (CT) has been recognized as an advanced agricultural technology that may reduce drought and improve the physical condition of soils worldwide. An increase in water infiltration and a reduction in water and wind erosion can be achieved through the use of no‐tillage, minimum tillage, and residue cover. In China, CT research started with support from the Ministry of Agriculture (MOA), China and the Australian Centre for International Agricultural Research in 1992. By the end of 1990s, CT research had expanded across China and achieved several important results. In 1999, MOA established the Conservation Tillage Research Centre (CTRC) to lead the national CT research programs in China, and since 2002 some CT demonstration projects have been established in northern China. By the end of 2008, CT has been demonstrated in 226 national and 365 provincial demonstration counties, covering more than 3 Mha. The CTRC of the MOA has established 10 sites within those counties to monitor project results. Some sites have shown consistently that the use of CT resulted in higher yields and net incomes, reduced soil erosion, and improved soil conditions. CT has been widely accepted in China and will be further adopted over wider areas as the development and highbred of indigenous no‐tillage seeders.

Soil physical properties and infiltration after long‐term no‐tillage and ploughing on the Chinese Loess Plateau

Abstract Water is the most limiting factor for crop production in dryland farming. A better understanding of the long‐term impact of tillage and residue management systems on soil structure and water infiltration is necessary for the further development of conservation tillage practice to improve water use efficiency. The objectives of this study were to assess the influence of no‐till with residue retention (NT) and conventional (plough) tillage with residue removal (CT) on soil properties and soil water transmission characteristics in a winter wheat (Triticum aestivum) monoculture system in Shanxi, on the Chinese Loess Plateau. Soil physical parameter measurements were made in the top 30 cm depth in September 2007 after 16 years under the two tillage treatments. Compared with CT treatment, NT significantly (P < 0.05) reduced soil bulk density (7.1%) in the 20–30 cm soil layer, and increased macroporosity (>60 μm, 17.0%) and saturated hydraulic conductivity (249%) in the 15–30 cm soil layer. There were no significant differences in these soil physical properties between tillage systems in the 0–15 cm layer. In addition, plant available water and water infiltration rate were greater in the NT treatment. The improved soil quality parameters and water infiltration from this long‐term experiment indicate that no‐tillage with residue retention is a promising farming system for the dryland farming areas of northern China.