New Conservation Tillage Technologies For Surface Irrigated Production Systems

K. D. Sayre

December 2000

Conservation tillage technologies, especially those that are characterized by zero or very minimum tillage with crop residue retention, have been largely restricted to rain fed production systems, to larger scale farmers and, except for Brazil and Argentina where tremendous progress in adoption of zero till has occurred, to developed countries. Furthermore, the adoption of conservation tillage to irrigated production systems has been extremely limited for both developed and developing country situations, except for some small areas where sprinkle irrigation is used.

In the vast gravity/surface irrigated areas which include well over 50% of both wheat area and production in the developing world (including China, India, Pakistan, Bangladesh, the Central Asian Republics, Turkey, Egypt, Sudan, Nigeria and Mexico among others), there has been essentially no development of appropriate, reduced/zero till technologies that can be easily implemented by farmers, large or small. At least this has been the case until the recent advances that CIMMYT agronomists have made in collaboration with their NARS cooperators in south Asia, mainly in the irrigated rice-wheat system, and in northwest Mexico in the irrigated wheat-maize or soybean system.

Irrigated Zero-till Wheat Planting after Rice In South Asia

In the early eighties, Dr. Peter Hobbs (CIMMYT wheat agronomist then but currently a CIMMYT NRG agronomist) initiated research in Pakistan to investigate the possibility to plant wheat after flooded, paddy rice using zero tillage seeding practices. The potential advantages for this approach included the opportunities to reduce production costs and minimize or even reverse the probable long-term, detrimental effects on production sustainability resulting from the considerable tillage being used. However, the main, immediate advantage to farmers was the dramatic reduction in the crop turn-around-time (harvest today, plant tomorrow) that zero till offered as compared to the normal, extended period needed for land preparation following rice harvest before wheat could be planted using conventional tillage (in some cases up to 3 weeks). Since wheat yields can be reduced by up to 50 kg/ha/day for each day past the optimum date for planting, timely wheat planting provides an immediate benefit to farmers.

Since no zero till planter appropriate to the predominately small-scale farmers in Pakistan was available anywhere, Peter and his colleagues initially modified a small, zero till planter imported from New Zealand (size scale was appropriate but it too costly to import and sell commercially in south Asia). The modified, imported planters were used to conduct numerous research trials in farmers' fields in many locations in Pakistan over several years and quickly demonstrated the multiple advantages of zero till wheat planting.

A local machinery company even began to manufacture a reasonably priced zero till planter based on the modified planter used for the research and farmer demonstration trials. However, largely because of skeptics (mainly uninformed researchers and research directors) unfamiliar with the technology or just plain ignorant, nothing happened for nearly another 15 years.

A similar situation was occurring in northwest India. Agricultural engineers at Patanagar University were able to modify the existing "rabi" wheat drill using the same “inverted T" openers that Peter had introduced with the zero till planters from New Zealand and had provided to the engineers as examples to consider. The modified planter with the “copied” inverted T openers worked well and was remarkably low priced. But, again, largely due to researcher/leadership skepticism to get behind the technology, nothing really happened for several years as occurred in Pakistan.

This was soon to change in both countries as a result of CIMMYT”s and Peter's continuing diligence, patience and persistence to find money to obtain some of the locally developed zero-till planters in both countries and to provide to interested NARS scientists and to support their continued testing and demonstration. However, perhaps the most important factor to bring about a dramatic change were two dynamic NARS scientists, Dr. R. K. Malik, weed scientist at HAU in Haryana, India and Dr. Mustaq Gill, director of the on-farm water management program in the Punjab, Pakistan. Both shared Peter’s deep conviction that new and more efficient, economical and sustainable technologies were needed for the rice-wheat system. They were also convinced that zero till wheat planting was the first step to take and they also believed that any further development required direct participation of farmers to insure that any needed modifications to the technology were concurrent with farmer requirements. Close farmer involvement was also believed to be necessary to enhance the rapid extension of the technology. They both developed the approach to place the zero till planters in the villages with farmers accompanied by remarkably motivated staff to work with the farmers.

The similarity of what has occurred in both cases is striking. From a modest start of about 50 total acres planted in a number of farmers' fields 2-3 years ago, each program had nearly 16,000 acres of zero till wheat planted during the 1999/00 wheat crop. Tremendous farmer demand exists for the zero till planters in both countries and manufacturers are striving to meet demand. At least 500 zero drill planters will be sold in Pakistan this year. Many farmers now realize that zero till wheat planting after paddy rice is a new, integral part of the normal production technology for the irrigated paddy rice-wheat cropping system.

Direct benefits that farmers are reaping in addition to higher, more stable yields from more timely planting of their wheat crop, include savings of up 98 liters/ha of diesel fuel by saving up to 10 tillage passes normally used to plant wheat after flooded paddy rice. Irrigation water savings average nearly 20% and many annual weeds like Phalaris minor appear to be less prolific under zero till. It is clearly a new production revolution that truly offers real progress towards making farmers' production systems more sustainable, input resource efficient and more profitable.

Clear lessons can be learned from what has happened in the province of Punjab in Pakistan and the state of Haryana in India concerning efficient procedures to introduce new, useful technologies to small-scale farmers. The technology obviously needs to address real problems and it must be tested and understood by the researchers and support staff who will be involved directly with farmers. Even these preliminary steps to develop the technology should strive to reach and use direct farmer participation as quickly as feasible (the reality test. Convincing farmers early on that a new technology provides major benefits is more important than convincing the office-bound administrators. Satisfied farmer groups can speak louder than most administrators.

Furthermore, when major changes are being made in farmer practices such as converting to zero till planting, always, new or modified, appropriate machinery/equipment will be needed. Someone needs to make sure that the proper prototypes are developed and that some entity will be able to build adequate numbers of good quality machines because, if not, it almost makes no sense to start anything since the effort will become largely academic and die in the water.

Therefore, the people lesson that has been learned is probably most important. The Hobbs are needed to be the catalysts. Then the Maliks and Gils must be identified for each potential situation and be allowed to confront the nay-saying skeptics, to convince the customarily indifferent leaders and administrators to provide the needed support. They must also have enough credibility to stimulate both their supporting staff, machinery manufacturers and the participating farmers to be equally convinced that a revolution can happen. Well, such a revolution is now well underway in the Punjab of Pakistan and in northwest India and the farmers are the winners.

Irrigated, bed planting systems in northwest Mexico

Irrigating crops by furrows/corrugations is not a new technology. It occurs in parts of west Asia (Turkey and Iran), in Pakistan and in China and is one of the more common irrigation systems in the western states in the USA. It is more commonly used for irrigated row crops like maize, cotton, dry beans and soybeans among other crops and is also used for small grains like wheat but normally with the small grain planted on the flat followed by making the irrigation furrows, usually 70-100 cm apart. The crop appears essentially as a solid stand since some seed ends up in the furrow.

However, irrigated wheat is by far more commonly planted on the flat with flood irrigation (especially by small farmers in south Asia and China) even though the same farmers may grow their other crops with furrow irrigation. In addition, almost all crops grown with surface irrigated systems combine heavy tillage with crop residue incorporation (maybe the minority) or crop residue removal, often by burning (probably the majority). Flood irrigation for wheat is practiced on essentially all of the 25 or so million ha of irrigated rice-wheat but there is at least that much area or more under surface irrigated production systems where wheat is grown in rotation with other crops besides rice. Given these circumstances, the changes that have occurred in farmers’ production practices over the past 25 years in northwest Mexico, especially in the Yaqui valley of Sonora has offered new opportunities for scientists and farmers to develop more sustainable irrigated production systems. It also is an example of farmers, themselves, taking the leadership to modify production practices, well ahead of most researchers and machinery manufacturers.

Twenty-five to thirty years ago, nearly all farmers in the Yaqui Valley planted their wheat on the flat and used flood irrigation. The wheat production system was characterized by use of extensive tillage and crop residue burning and by heavy dependence on herbicides for weed control. Today more than 95% of the farmers plant their wheat on beds and use furrow irrigation (70-100 cm between the furrows). The major innovation that farmers introduced was to plant 2-3 defined rows on top of the bed spaced 15–40 cm apart depending of bed with and row number instead of. This simple planting modification offered new wheat management options that allowed farmers to dramatically improve production efficiency and reduce production costs. Simply changing to furrow irrigation realized an average savings of 25% in irrigation water. However, by planting 2 or 3 defined rows of wheat on top of the bed, farmers were able to utilize management practices or gain new advantages for wheat similar to other row crops including the following:

- Use of pre-seeding irrigation, which allowed a large part of the weed population to be controlled mechanically at planting and enhanced crop establishment, especially for heavy, crust-forming soils.

- Use of mechanical weeding in the furrows and between the rows after crop emergence which, combined with the pre-seeding irrigation, has reduced herbicide use from about 70-80% of farmers 25 years ago to less than 10% at present.

- Band application of fertilizers in the bed at planting, followed by banding of side-dress Nitrogen at critical times after crop emergence (instead of the more inefficient broadcast application or application in the irrigation water) which can dramatically improve N use efficiency and enhance grain quality.

- Reduce crop lodging since the new planting system reduces intra-plant competition and allows the use of lower seed rates.

The clear advantages that planting wheat on beds offered the farmers in the Yaqui Valley and the rapid adoption was instrumental in for the wheat program to decide that the technology was likely to be useful in other similar areas, especially where irrigated wheat was being grown in rotation with other upland crops but in some situations were wheat grown in rotation with rice. In about 1994, a program was initiated to bring visiting scientists to Mexico during the wheat crop cycle in Obregon to learn about the bed planting system and to test its utility in their home areas. Since 1994, over 39 agronomists have been trained in bed planting, mainly from Asia, but also from Africa and Latin America. Currently research, development and extension programs for bed planting are underway in India, Pakistan, China, Iran, Turkey, Sudan and several CIS republics. In most cases, similar improvements in production efficiency are being obtained including irrigation water savings of 25-50%. Again, the lack of appropriate bed planting machinery has been a common constraint but each country is working on machinery development. The assistance of Peter Hobbs and his colleagues in south Asia has been instrumental in achieving the progress in testing the bed planting system and in developing appropriate scale bed formers and bed planters for the farmers. Dr. Raj Gupta, facilitator of the Rice-Wheat Consortium, initiated trials this past summer to investigate the feasibility of growing rice on beds in rotation with wheat in India. He and his colleagues obtained some extremely favorable results including a savings of over 50% of the irrigation water and more that 3500 Rupees per ha as compared to transplanted puddled, flooded rice and grain yields were similar for both systems.

Farmers in the Yaqui Valley continue to use fairly extensive tillage and considerable crop residue burning. However, with the bed planting system farmers quickly realized that if a common bed width was used for all crops in their production system including wheat, an opportunity to reduce tillage by reusing the same bed for succeeding crops was possible. Therefore, a very common practice is to perform tillage for the wheat crop, make new beds and plant wheat but after harvesting wheat, the straw is removed for fodder or burned (most common) and the same beds are used to plant soybean. Tillage again is performed after soybean harvest prior to planting wheat or another crop.

The burning is practiced because of a lack of planters that can plant soybean of maize into residue. Similarly, no commercial planter exists that can plant 2-3 rows of wheat on top of a bed into residue and without tillage. However, the opportunity was there with the bed system to develop a dramatically reduced till, residue managed wheat production system for surface irrigated situations.

In 1993, I initiated research in the Yaqui Valley to develop a permanent bed system for the irrigate wheat-maize or soybean system by which tillage is reduced to a simple reshaping of the bed following harvest of one crop and before planting the next. Residues are chopped and evenly distributed. A great deal of time and effort has gone into developing appropriate machinery to reshape and plant on the permanent beds. Very sound machinery prototypes have been developed and trials comparing permanent beds planting systems using different straw management regimes with conventional till beds have been ongoing for 8 years. Results over the 8 years indicate that the permanent beds are better yielding, especially when all residues are retained as compared to the conventional farmer practice and that production costs are reduced by nearly 25%. We are beginning to extend this new technology to farmers in northwest Mexico and to train scientists from other countries to extend the technology to other similar areas.

The use of the permanent beds provides the first real opportunity to reduce tillage and retain residues which lead to marked improvements in soil physical, chemical and biological parameters and improved water use efficiency, especially in the hot summers due to the residue mulch effect. The permanent beds also allow more opportunities manage fertilizer (especially N) more efficiently due to field access to band the fertilizers when and where needed. Permanent beds also provide a built-in controlled traffic system to reduce compaction since all machinery wheel traffic restricted to the bottom, not on the bed top where the crop is growing.

Hopefully, this system will continue CIMMYT’s mandate to offer sound, productive and sustainable production systems to the developing world’s farmers.