Under certain conditions traditional monsoon rice in Asia that is hand transplanted into puddled soils can be ecologically sound and robust. A long term experiment at IRRI found, for example, that soil organic matter increases in flooded fields, even when farm workers cart away, three times a year, all above-ground crop residues along with tons of grain. "Well-managed irrigated rice ecosystems are masterpieces of ecological vitality and sustained productivity," observes IRRI scientist Roland Buresh, who manages the experiment.

Yet most of continuous rice systems have converted or are converting to rice / other crops due to nutritional and economic needs of the farmers. Unfortunately, the health of their soils under these new cropping systems is deteriorating.

CIMMYT and RWC and their national research center partners in Pakistan and India successfully introduced 4-wheel tractor based zero till wheat into the western Indo-Gangetic plains rice – wheat cropping system (by some estimates currently puts adoption of zero till wheat at over 2 million hectares in Pakistan and India's Punjabs and India's Haryana and western UP). Work soon turned to bringing zero till and conservation agriculture to monsoon rice because their own research was showing that this "hybrid" zero till wheat -conventionally puddled rice system could prove even more detrimental to the soil health (see a recent FAO paper on this hybrid system).

By simply applying the highly successful 4-wheel tractor (winter wheat) zero till machinery to rice crop establishment much of the early work has shown that researchers were able get yields equal or better than transplanted rice. Though new and fairly complicated agronomies and weed control measures had to be developed it is reported that in the well drained soils of the northwest Gangetic plains, there is increasing adoption by farmers of zero till rice using the conventional zero till wheat seeder.

Yet, there have been problems when applying the 4-wheel tractor zero till machinery to the heavy soil lowlands of the eastern Gangetic plains. For years now when we in Nepal through our experiments and farmer field demonstrations could successfully direct seed rice (DSR) with machinery into the ground, and get it out safely out of the seedling stage, and control the weeds, then we too obtained yields equal or better than transplanted rice (see recent Paper from AIRC, NARC). Yet, there are two main technical problems though in the eastern Gangetic plains lowlands for zero till rice. The first big problem and major risk to farmers is that 70 % of the area of eastern Gangetic plains is lowland that has no drainage outlet. This means that any directly sown and just emerging rice seedlings are at risk or drowning from prolonged submergence (24+ hours) in early season downpours. Once the seedlings are 10-15 centimeters (two to three weeks of growth) they are generally out of harms way but not always as seen by the recent floods in August 2007 of the eastern Gangetic plains where large areas of the traditional and taller hand transplanted seedlings were drowned bringing great misery to Bihar and Bangladeshi farmers. The second big obstacle is that early intermittent pre-monsoon rains can keep large tractors out of the field. Last year (summer 2006) around Birganj, Nepal there was nearly 90 hectares of DSR with 2 wheel and 4-wheel tractors. This year due to early intermittent rains farmers could not get their big tractors/seed drills into the fields due to high moisture (they would sink in the mud). So there is less than 20 hectares DSR this year.

To get around both the above problems two year ago NSAE and it's partners National Wheat Research Program, NARC began working on two new methods of zero till machine and hand transplanted rice (see recent description in Zero Till Transplanted Rice). Though still in the research phase we feel that these methods not only can solve the problems of seedling mortality and field access by machinery but that it offers very poor farmers who might not have access to machinery the chance to benefit from zero till / conservation agriculture rice. It has problem but also good possibilities I think for areas of Asia that still haven't mechanized rice transplanting. The original idea comes from southeast China where Peter Hobbs reported seeing it being used by farmers there over 10 years ago.

Evaluation of Non-Puddled and Zero Till Rice Transplanting Methods in Monsoon Rice Paper presented at International Agricultural Engineering Conference, AIT Bangkok, Thailand 3 – 6 December, 2007.

Conservation Agriculture Rice Paper FAO courtesy Dr. Theo Friedrich

Paper from AIRC, NARC