August 30, 2023

AGRONOMY NEWS

Farms Find Benefits With Off-Season Break Crops

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Cash flow, an opportunity to make a bit of profit, improve the soil, and to try out new crops in a lower-risk situation. It may seem a long way off, but these are the reasons why some of the very progressive farmers I work with use off-season crops after maize or wheat.

For most farmers who are more familiar and confident with wheat or maize, growing a different crop on a big area in their main season can be an uncomfortable prospect. At least trying it in the off-season gives a chance to see how it performs and to learn a bit about the crop.

Ultimately, to break the cycle of weeds, pests, and diseases a proper rotation is required – particularly for grass weeds such as Brome – and farmers will need to take the jump and plant break crops in their main season. But to get started, experimenting in the off-season is a much lower-risk approach.

Some of these crops provide very good soil structural benefits, with sunflowers and canola producing deep taproots with help open up the soil. Legumes such as peas and faba beans fix a lot of Nitrogen for the following crop, and these provide significant benefits for the next planting of maize or wheat in March. They also provide good ground cover to help control weeds – far cheaper than multiple sprays of glyphosate. And ultimately they bring in more money from the shamba.

We take a look at some of the options below….

Sunflowers

Sunflowers make an excellent break crop for the off-season, particularly in areas with low Short Rain reliability. They are a crop that can get by on 200mm of rainfall but do need significant spending upfront on fertiliser, seed, and pre-emergence herbicides especially. Birds at harvest are a real challenge, but they are very reliable in dry seasons.

Peas

The true attraction with peas is the fact that they can be ready to harvest in a little over 110 days in most areas, providing a quick return and fast cash, and being easy to sell in local markets. Harvested dry with a combine, peas do have significant up-front costs however, so farmers do need to be confident of a return. They need reasonable rainfall and a good soil structure, so if you have disc ploughed for 10 years, stay away from peas until you have put a chisel into the soil.

Lupins

Are a relatively new crop but many wild species are commonly found across Kenya. Very drought tolerant with a deep taproot, lupins should only be planted with the appropriate lupin inoculant (they won’t fix any Nitrogen otherwise – Lachlan and others can help supply this), but they are easy to grow and harvest once established.

Linseed

This has the potential to become an important crop over the coming years. Quite drought tolerant, plenty of herbicide options, relatively fast maturity in 140 days, and a fantastic break crop for root structure, reducing nematodes and all manner of root diseases. Plus easier to plant than sunflowers, sorghum or canola. The market needs development but watch this space.

Chickpeas

Easily the most drought-tolerant legume, Chickpeas are a great crop in dry areas which right now are very sought after and easy to sell. You do need to be attentive to insect pests, mainly bollworm, and they can take 160 days to mature even at lower altitudes. Relatively well adapted to most soil types, Kabuli Chickpeas can be planted well with an Ndume airseeder.

Mungbeans (Ndengu, Greengrams)

Another great pulse crop for hot areas, require minimal moisture but do prefer heavy soils. Not a crop that thrives on the sands in Trans Nzoia (Kenya) for example. They are not the most competitive crop early on, and planting needs to be precise, so start small with Mungbeans, and be ready to harvest in good time before the pods shatter and lose the seeds.

Sorghum

Sorghum in theory grows very well in the hot off-seasons of most areas of the country, but many people confuse this with drought tolerance. It is a crop which still requires several hundred mm of rainfall, and the fact that it is so similar to maize limits its role as a break crop. Birds at harvest, poor availability of varieties and limited benefit for the following crop mean that sorghum struggles to justify a place unless after a main season break crop.

Sorghum being grown as it should be; a main season crop to maximise its potential, with a fast pulse perhaps planted after it in October.

Canola
Hyola Blazer is probably the best variety for this situation, being the fastest maturing and most drought tolerant as canola goes. Canola does need moisture in the soil and right through to flowering, however, so I always advise farmers to make a sensible decision before they plant as to whether they are likely to get the rain that the crop needs. Great herbicide options, good break crop for structuring the soil, and birds are much less of a problem than sorghum or sunflowers.

Off-season crop gross margins

*Upfront costs include seed and seed treatment, planting fertiliser, and pre-emergence herbicides.

Sunflower Weed Control

Good weed control in any crop is essential to remove the competition that can be so damaging to yields, but also to avoid the need to cultivate and loosen soil later on in the crop which presents an erosion risk and danger to water quality.

Depending on where you are in the world and what chemistry is approved, pendimethalin is a great starting point which is very safe on the crop and controls a range of broadleaved weeds. S-metolachlor is also very useful because it adds Blackjack control and improved activity on Amaranthus.

Weed control in sunflowers, unfortunately, carries a lot of upfront costs (see Gross Margins table earlier), but when done properly it is very rewarding.

Clomazone is safe, only when applied pre-planting (NOT pre-emergence). It is borderline safe as a pre-em, but if you can apply ahead of the planter and throw a bit of soil away from the row it really helps especially where Cleavers are a concern (if you apply pendimethalin pre-em, post-planting this – combined with the crop competition – will be enough to control cleavers in the actual crop row).

Where brassicas and Nightshade are likely to be an issue, Acetochlor helps but linuron is really good, particularly on Nightshade.

Remember that grasses can be removed with fluazifop / propaquizafop / quizalofop / clethodim later so these should not be a concern for the pre-em herbicide. If you are planting sunflowers straight after a cereal crop however and volunteer wheat or barley pressure is high, take them out with a spray by the time they get to 3 leaf stage to avoid checking the sunflowers.

Oxyflurofen is a useful addition to pre planting sprays and has some residual activity, so worth considering adding to glyphosate ahead of planting.

Tyres, Traction and Ballast

Whether you are running a 400hp tractor with a 9m wide maize planter or have a contractor bringing their 70hp tractor and four-row machine, you have a lot in common; the only contact between the tractor and the soil to put that power down is the tyre. It also determines how all of that weight is transferred to the soil with significant implications for soil structure and the growth of your crop. Here are a few golden rules:

  1. Run the correct tyre pressures. This allows you to optimise the footprint or contact area of the tyre with the ground and reduce soil compaction. Remember to follow the manufacturer’s guidelines (the tractor’s handbook or the tyre manufacturer’s website), and that lower pressures also mean lower road speed and reduced load capacity. For planting and cultivations, most tyres allow you to go down to 0.8 bar, and in recent years 0.5 and 0.6 bar rated tyres are not uncommon.

  2. When you get back to doing mainly road work for example pulling a trailer at harvest, remember to re-inflate the tyres to the recommended road pressure, typically 1.6 bar but always check. The time it takes is a matter of minutes and it means greater tyre life, lower fuel use and better safety.

  3. If you think your tractor is slipping when pulling a heavy cultivator, there is any easy way to check. Measure the rolling circumference on a hard surface where there is no slippage; draw a marker on the side of the tyre so that someone can count revolutions for you in the field; do 10 revolutions and measure the distance travelled. Realistically it should be around 85-90% of the actual distance.

  4. If the tractor is bouncing and losing traction to wheel slip, you may need to add ballast either as wheel weight or on the front weight frame. Bridgestone Tyres have a very useful App to help calculate and optimise tractor ballast.

Poor soil structure is one of the greatest causes of yield loss in Kenya. The soil needs to be able to store water, oxygen, and allow roots to grow down and access nutrients without hindrance.

The two shocking facts are that A) irrigation does not solve this – you cannot irrigate with oxygen as obvious as it sounds, and the roots still cannot explore and access enough nutrients from the soil! B) Avoiding soil compaction generally SAVES YOU MONEY! Less fuel, less tyre wear etc. For most farmers I visit, soil structure and crop rotation are the two easiest wins they can achieve.

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