Promotion of conservation agriculture using permanent raised beds in irrigated cropping in the Hexi Corridor, Gansu, China

• China Agricultural University, China
• Gansu Academy of Agricultural Sciences, China
• Gansu Agricultural Mechanisation Bureau, China

Gansu is a north-western Chinese province in the Yellow River Upper Drainage Basin. Between Gansu and neighbouring Inner Mongolia lies a distinct valley, the Hexi Corridor. In the past, reliable snowmelt water from the adjacent Qianlian Mountains has sustained the irrigated agricultural areas along the length of the valley. In more recent times, reduced snowmelt water has led to significant reductions in available surface water, whilst over-extraction and decreased recharge has lowered water tables in groundwater driven systems. As a consequence farmers are facing severe water restrictions (up to 50% reduction in allocations). Better channel lining has reduced delivery losses, but farmers have received few practical solutions to cope with the policy-driven cutbacks in water allocations, water price increases and pumping costs. Other food production issues associated with water restrictions - for example small farms, low levels of mechanisation, high inputs, conventional tillage, low incomes and the loss of young men to the cities - are placing further pressure on farmer livelihoods. Therefore this project examined and tested conservation agriculture, using practises such as zero tillage and permanent raised beds (PRBs) to reduce irrigation water use, maintain farm yields and improve farmer incomes.

Therefore this project is examining conservation agriculture, using practises such as zero tillage and permanent raised beds (PRB), to reduce irrigation water use, maintain farm yields and improve farmer incomes.

Preliminary studies by the Gansu Academy of Agricultural Sciences (GAAS) have demonstrated the effectiveness of PRB farming, showing similar water productivity and yield gains to those found in PRB systems at the Shandong Academy of Agricultural Sciences (SAAS), the Indian subcontinent, Australia and Central America. Key constraints to the practical implementation of these elements of conservation agriculture in Hexi are; the lack of appropriate machinery, farmers are steeped in conventional tillage and flood irrigation methods, competition for crop residues and whether or not an economic benefit exists from implementation of PRB in this region. The Australian project leader has a long term working relationship and significant academic connection with the Chinese project leader, his predecessors and associates, originating from LWR2/1996/143. The Chinese project leader has a strong relationship with the Ministry of Agriculture (MOA), Provincial Agricultural Mechanisation Bureaus (AMB) and Farm Machinery Extension Stations, each of which will facilitate, support and establish the proposed RD&E in Gansu and through leverage of significant additional MOA funds. Generally, the Gansu AMB (GAMB) will drive and support the demonstration sites across Hexi Corridor and thus the extension of PRB and conservation agriculture. Provincial and county organisations, plus lead farmers and members from the water resources bureau, will form a project steering committee, who's role it is to oversee the rollout of PRB, initially within the county, but in subsequent years, beyond it.

This 4-year project was based on the premise that conservation agriculture (CA) using permanent raised bed (PRB) technology could save water without yield penalties. The project team worked with farmers to successfully test a bed former, a 20 hp tractor-mounted wheat harvester and an integrated mechanical and chemical weed control implement, and later identified factories for commercialisation. The team also developed a tactile implement guidance system to facilitate precision planting.
Prototypic lightweight zero till (ZT) planters based largely on local capacity were built and assessed. However, testing showed that soil disturbance was too high, slot closure inadequate and residue handling poor. A final version built in eastern China showed great promise, but still required minor modifications to cope with heavy residue, poor soil flow and adjustability to suit various soil and planting conditions.
Under research conditions water savings were up to 43%, with minimal soil salinity accumulation. Average PRB wheat yield (6.4 t/ha) increased marginally. In contrast, due to low soil temperatures at planting, average PRB maize yield (11.3 t/ha) was 20% lower than conventional farming.
Average water saving for PRB in three on-farm demonstration sites established in the northern, central and southern Hexi Corridor was1.5 ML/ha (28.13%). Advances in on-farm comparative yield were not significant. However, PRB had significant economic, social and environmental benefits, which can be extended across the Hexi Corridor. On-farm data suggest a 2% annual increase of PRB adoption over 5 years would produce accumulated water savings of 2,520 GL.
A cost-benefit analysis revealed that PRB recorded reductions in water use, diesel use, labour input and machinery costs, totalling $312/ha less than conventional farming and producing a $318/ha higher net profit. However, PRB maize recorded an average loss of $92/ha. The increases in net profit were not considerable, but in relation to input costs and the low cost of living in the region, they could provide a substantial benefit to farmers in the longer term.
Capacity building included extension, monitoring and measurement, CA farming, mechanisation and trainer courses for 160 technicians and 45 researchers. Elements were conducted in Australia, Canada, various Chinese provinces, major cities in Gansu and at the demonstration sites. Project members and 2,000 farmers learnt a new and easier method of farming, which facilitated advances in water saving technology and machinery development many years ahead of current practices. With a greater appreciation of sustainable farming techniques they have extended fresh raised-bed farming to about 33,000 ha. Though not yet agronomically or economically sustainable, it was considered an interim step toward conservation agriculture until suitable PRB zero-till (ZT) machinery and weed control technology for ZT farming become available. These were the only issues limiting the broad adoption of CA in Gansu.
PRB as part of CA technology is on the cusp of rapid advancement in northern China. The Provincial Government in Gansu is promoting PRB as one of three key technologies for water saving; also the Ministry of Agriculture and Department of Agricultural Mechanisation have expressed keen interest in promoting PRB in northern China. So the resolution of the performance issues of the lightweight planter is of the highest priority.