The Do's and Don't's of CRP take-out
The Do's and Don't's of No-Tilling Arable Crops into CRP Ground
Dr C John Baker, CEO, Baker No-Tillage Ltd, Feilding, New Zealand and Pullman, Washington, USA
It seems that everyone is astonished by those who claim that no-tilling into sod is easy. But it really can be so with the right equipment. Nonetheless, let's be clear what we mean by sod. The fairway of a golf course is a vastly different proposition from Conservation Reserve Program land. But both could be described as sod and the same machinery can be used for both. The key element in both is a dense network of fibrous roots close to the soil surface. The difference lies in what is above the soil surface. Mown grass is characterised by tightly-packed short orderly plants. CRP land might be better described as a 'low-flying jungle' .
In relation to CRP, there are two main considerations.
The first is how to physically cope with the tangle of grasses, weeds, legumes and perhaps pests without (a) blocking the machine, and (b) destroying all the good biological things that have happened to the soil in the past 10 years?
The second is how to create a biological environment that favours and protects the newly-sown crop, but also harnesses the wonderful biological assets that 10 years of non-production will have carefully created and nurtured?
Sadly, the problem of physically handling the biomass often compromises the issue of making best use of it. But it need not be that way.
To understand how best to handle the situation, it is necessary to understand where this particular author comes from and what has dominated his no-tillage experiences to date. The author is from New Zealand where most agricultural production centres on pasture production even although arable cropping is also viable and plays an important role. It is the interface between these two systems that is of most relevance to re-cropping of CRP land because that is essentially what New Zealand farmers have been doing virtually on a daily basis for a couple of hundred years.
The structure and productivity of New Zealand soils deteriorates just as quickly, and its tillage methods are just as destructive as in North America. But New Zealand has the advantage of a benign climate that allows two things to happen: (1) Grass-fed animals remain on fields all year around, and (2) New Zealand seldom sees lying snow on agricultural land for more than a few days and it is seldom so cold that winter growth stops altogether. It just slows down compared with spring or autumn. Animal production is therefore regularly integrated with cropping by the same farmers. Double cropping is common. Rotations often start when cropped soils deteriorate so badly (after, say 3 - 5 years of double-cropping) that farmers revert to a similar period of continuous pasture in order to attempt to repair the damage. Rotation and integration are therefore household words in New Zealand farming.
Often dairy cows are wintered on specially-sown winter forage crops. This is done by arable farmers on contract to dairy farmers and provides a convenient source of additional income for the arable farmers between summer crops. But such a system also tests soil sustainability to the limit as the heavy dairy cows cause much treading damage during the wet winter months in which they sometimes find themselves standing in mud up to their knees. No-tillage of the forage crop in the first place reduces treading damage but light surface tillage is occasionally necessary after the cows have been removed to return the soil to productivity. Fortunately, it is unlikely that CRP land will experience such extremes.
Other New Zealand systems involve substituting a succession of short-duration forage crops (including hybrid grasses, cereals, bassicas, legumes and herbs) for long-term pastures in order to maximize meat, wool and milk production from sheep and cattle. Such intensive, high-production forage crops may have growth-cycles of less than 6 months, making reseeding a frequent and repetitive undertaking that relies heavily of fail-safe no-tillage. But 50+% gains in dry matter production are common, compared with long-term pastures, and this translates directly into profitability.
Still other systems involve pasture renovation in which long-term pastures are improved by injecting improved species at regular intervals into the base pastures without their total destruction.
All of these systems either benefit from, or are totally reliant upon 'fail-safe' no-tillage. In some cases seeding takes place twice (and even three times) per year. More importantly, because pastures play such an integral role in New Zealand agriculture, much of the no-tillage seeding is into sod. Indeed the original objective of developing New Zealand's Cross Slot® no-tillage system in the first place, was to find a way of seeding successfully into sod.
Applying these every-day undertakings to the specific case of seeding into CRP land, the following principles will apply:
- The worst possible thing that can be done to CRP ground is to till it, even once.
- Sowing a cereal as the first crop after CRP should not be a preferred option although it can be done. Sowing a broad-leafed crop first time up is preferable because the pests of grasses are often also the pests of cereals.
- After spraying with an effective herbicide, CRP land should behave like, and be treated as if it is heavy crop residue.
- Because much untouched CRP land will not have been cut, residue handling by machinery should, in fact, be easier than when dealing with cut and lying cereal residues.
- Where silage or hay can be harvested before CRP land is cropped again, residue handling will be greatly simplified, especially for non-disc-type openers.
- Effective weed control is crucial, and this involves accurate identification of the species present and perhaps creative blending of two or more herbicides.
- Knowledge of herbicide compatibility will be important.
- In many cases, the New Zealand practice of spraying long grasses with glyphosate followed by harvesting for silage or hay, 2-4 days later, will be applicable prior to drilling of the new crop.
- This practice tests farmers' confidence that the glyphosate spraying will be effectively translocated to the grass roots, since removal of the leaf material for silage or hay disguises any obvious die-back for quite a while. But the practice works!
- Some pesticides are compatible with glyphosate and can also be applied to the grass material to be cut without detriment to stock.
- Many pests of grasses that have flourished unmolested for 10+ years under CRP are also pests of cereals. Be sure to identify pests carefully if contemplating sowing a cereal first.
- Beware of slugs (molluscs) and rodents, which are pests that thrive within dense sod and do not care what they eat. They might not have been a problem in the past but could easily be so after CRP.
- Decomposition of CRP biomass will likely temporarily 'lock up' large quantities of soil nitrogen after spraying, leading to poor initial growth of any crop and even yellowing.
- This can be compensated by judicious application of nitrogen at sowing, but only if it can be safely banded separately from the seed.
- Broadcasting of fertilizer (including nitrogen) will usually give disappointing results.
- Many double-shoot openers that can band fertilizer and seed at the same time are non-disc (shank) types that block in heavy residues and therefore cannot be used without at least surface tillage or harvesting as silage or hay.
- On the other hand, most disc-type openers (that can handle the residues) do not double shoot fertilizers effectively and are likely to hairpin in heavy residues anyway.
- Therefore the choice of which no-tillage openers to use is limited and is why many people reluctantly revert to tillage.
- But Cross Slot openers revel in such conditions and indeed were designed specifically for them.
- Cross Slot openers create horizontal slots by hinging up two soil flaps (one on either side of the slot). The anchorage provided by sod roots aids this process, whereas it is detrimental to almost all other no-tillage openers that create vertical slots.
- Although drilling with some openers can take place within a day of spraying, the performance of all openers (including Cross Slot) will improve as the interval between spraying and seeding widens because the soil becomes increasingly drier, warmer and crumblier.
- But too big an interval will risk rain and the regeneration of weeds after spraying. The weed seed pool will be vast under CRP, and if it rains between spraying and seeding be aware that dying grasses no longer transpire water, which may delay drying of the soil again after rain.
- In extreme cases, a 6 or 12-month chem-fallow may be necessary to allow biomass decomposition to progress to a manageable level and/or to target regenerated weeds and eliminate pests.
- If spring seeding is contemplated, it is important to realise that the soil will warm up more slowly anyway than in the fall. This may influence the planned interval between spraying and seeding.
- It may also affect the choice of spring-sown crop to be grown after CRP, favouring crops that can be sown later rather than earlier.
- It is one thing to be critical of how previous generations turned the virgin prairie sod into a dust bowl. It is now our turn to demonstrate how it should have been done in the first place.
Let's hope that current famers do not simply repeat history