Soil scientist's functional definition:
Intentional destruction of soil structure by doing tillage under floodwater, which squeezes air out of pore spaces, breaks clods, and forms a hard pan.
Rice scientist's explanation of purpose:
To make it easier to maintain 5-cm depth of water over the field during most of the season, which improves weed control (because many weeds don't survive the anaerobic soil environment) and enables optimal nutrient availability in most soils (pH goes towards neutral, at which most nutrients are relatively available).
- Destroyed soil structure makes it difficult to manage other crops in a rotation
- Difficult to pull tillage implements through submerged soil
- Extreme opposite of "no-tillage", which is sometimes promoted as the enivironmentally-friendly option in other cropping systems (because in a non-flooded system, no-till techniques preserve organic carbon, maintain good soil structure and good drainage, supply mulch to suppress weeds and maintain soil moisture)
We have chosen to puddle our soil (in plot 826), because:
- it is a good way to control weeds (of which there are many, especially volunteer rice growing from the leftovers of last season's combine harvesting operation)
- this field has been puddled many times before
- this field has no irrigation limitations
- we have access to good nutrient management recommendations for flooded systems
- it is not very risky
a) How many field operations after land has been soaked?
- 2 passes with plow, 1 with harrow/leveler
- 1 pass with plow, 2 with harrow, 1 with plank for leveling
- (why not just one harrowing? I suppose I'll find out soon enough)
b) What equipment for first (deep) plowing?
- 4-wheel tractor with moldboard plow
- 4-wheel tractor with disc configured for "plowing"
- 2-wheel (i.e. pushed by a person) tractor with moldboard plow
- 2-wheel tractor with disc plow
- carabao with moldboard plow
- (no one mentioned disc plows for carabaos; do they exist?)
c) What equipment for harrowing (which means a shallower tillage done after plowing, designed to pulverize the clods to really destroy the soil structure well):
- 4-wheel tractor with disc configured for "harrowing"
- 4-wheel tractor with rotavator
- 2-wheel tractor with rotavator (called "hydrotiller", I think)
- 2-wheel tractor with rotavator plus a special adaptation with wide "pontoons" for use in deeper water (called a "floating hydrotiller", I think)
- something that can be pulled behind a carabao (I don't know what)
- something else that can be pulled behind tractor, has finer blades, and is appropriate for use in very very wet conditions (I don't remember its name, or understand when it should be used, since all puddling is in very very wet conditions by definition)
d) What equipment for leveling?
- 4-wheel tractor with laser leveling system (usually part of a harrowing operation, I think)
- 4-wheel tractor with non-laser leveling tool
- 2-wheel tractor with non-laser leveling tool
- carabao pulling a plank
- human pulling a plank
Although we have decided to do "puddling", all of these decisions are yet to be made. The field operation we did today (aerobic disk plowing with 4-wheel tractor) is considered a fallow management operation (rather than a land preparation operation that is part of the true "puddling" process). We visited the machine shed today and got a brief tour of the options. Our team has decided we want to do as many field operations ourselves as possible, which demotes the 4-wheel tractor and carabao options to the bottom of the list (since none of us can drive a tractor, or knows a particular carabao well enough to get it to cooperate). We believe ourselves to be capable of pushing a 2-wheel tractor, primarily based on the information that some of us did it once for a few meters during a CESD event.
If any of my readers would like to help clarify the options or implement names in my lists above, please help!