Growing Nitrogen Fertilizer
with Clover Green Fallow
"Quality not quantity" may be this small farmer's philosophy, but Ian Smith is growing enough legume biomass during his green fallow to completely eliminate the need for nitrogen fertilizer in the following crop.
Ian Smith
145 ac
Argyle, Manitoba
Precip: 403 mm/year
2004 acreage:
Barley: 45ac
Barley + clover: 45 ac
Clover green-fallow: 55 ac
Ian Smith farms the quarter-section of land north of Argyle Manitoba that was purchased by his father in 1953. Although a relatively small landbase, the three fields produce sufficient feed barley for Ian's farrow-to-finish hog operation which is directly marketed and delivered to customers. This is complimented by 53 laying chickens and a small cattle herd maintained off-farm over the cropping season.
Ian's introduction of a green fallow to the cropping system is an evolution from the black summer fallow employed by his father, which Ian later changed to back-to-back cropping. However, the decrease in crop yields despite rising input costs made Ian consider a new approach. In 2001, Ian established yellow (sweet) clover under the barley crop for a subsequent green fallow. He has since required less herbicide as the clover suppresses weeds under the crop, and synthetic fertilizer is not necessary in crops following the plough-down of the legume.
Ian's Green Fallow Containing Crop Rotation
Located in the moist black-Interlake soil zone, the fields are clay-loam or clay with pH 8.6-8.7. There are some alkaline-saline areas and potholes with constructed channels for drainage. The farm receives 403 mm average annual rainfall.
The aim of Ian's 3-year barley-barley-green fallow rotation is to produce quality feed for the pigs by improving the condition of the soil. Clover is established with the second barley crop and ploughed in during the following green fallow year to improve soil physical structure, water-holding capacity and drainage, and fertility to reduce fertilizer requirement.
Ian commenced the system with sweet (yellow) clover, but found it did not establish in wetter areas. He now sows a mix of yellow clover for height and biomass, and the waterlogging-tolerant, low-growing red clover to create an understorey.
| Field 1 | Field 2 | Field 3 |
|---|---|---|
2002: Barley + clover |
2002: Clover green-fallow 2003: Barley 2004: Barley + clover |
2002: Barley 2003: Barley + clover 2004: Clover green-fallow |
Ian measures the development of his barley crop following clover green-fallow. Field 1
Following the clover plough-down in 2003, fall soil tests indicated that applied N was not necessary for the following crop, and only negligible amounts of P and K (5-10 units and 10-20 units) were recommended, therefore no fertilizer was applied.
'Conlin' barley harvested on the farm in 2003 and cleaned was sown at 108 lb/ac. Like many properties in Manitoba, Ian received 18" of snow on May 10, but unlike many growers he had already cultivated, harrowed and sown his crop by May 9. He attributes the moisture for early seeding to improved soil structure, water-holding capacity and organic matter levels created by the green fallow.
In June, Ian had the field scouted and decided to spray 0.5 L/ac Spectrum on June 18 for Canada thistle although no wild oat control was required.
Field 2
Clover seedlings undersown to barley.'Conlin' barley was sown in field 2 with a press drill on May 8-9, 2004. In other years clover seed is blended with the fertilizer and 'floated' on and harrowed the day after seeding the barley. However in 2004 this did not occur until the field was trafficable again on May 23.
The clover was sown at a rate of 10 LB/ac and a cost of $1.60/lb. It was applied with 75 LB N, 20 LB P and 15 LB K as recommended after the soil test, which cost $42/ac including application. Ian notes that although the barley in field 2 emerged faster and is slightly thicker than field 1, the $40/ac of fertilizer applied means it must yield 20 bushels/ac more to be competitive with Field 1 on costs.
Clover seedlings under barley crop a week before swathing.The late establishment of the competitive understorey resulted in mustard and wild oat populations which required control with Assert on June 18, but no Canada thistle emergence. Ian is intolerant to wild oats which reduce the quality of the pigs' barley feed mix, however a second flush of wild oats was evident before harvest.
The barley crop is usually swathed in mid-August when the clover is 6-8" high, however Ian doubts it will be so advanced this year and the barley will not be dry until early September. The barley is combined and the straw baled, inevitably including some clover which Ian believes is an excellent mix for over-wintering cattle. The cattle will return to the farm after harvest and graze the clover until snow accumulation forces them indoors for the winter. The barley straw/clover bales are low cost and sweet, therefore Ian is not required to add molasses to encourage the cattle to eat.
Red (foreground) and yellow (background) clover mix - the key to Ian Smith's fallow system.Field 3
Following harvest of the barley cover-crop in 2003, a soil test in the seedling clover revealed that the two barley crops had depleted N levels by 85-95 LB/ac. By allowing the clover to regenerate in 2004 and ploughing in the biomass, Ian hopes the green fallow will rectify this but will confirm with soil testing before the 2005 barley crop.
The rapidly growing clover was dormant over the winter but in spring achieves Ian goal of "growing nitrogen" with clover plants up to 7'9" tall. This year Ian cut 2.4 t/ac of hay before ploughing down the remainder in late July with an 80 ft moldboard to 5" depth. The field was then leveled off with a double disk machine 2-3 days after ploughing. This process ensures the biomass is sufficiently broken down and incorporated for optimal mulching and nutrient release before next season. In spring 2005, the field will be cultivated, harrowed twice and sown to barley, hopefully with no additional fertilizer required.
Pest Control
Weeds
Ian employs numerous strategies to reduce the weed pressure in his grain crops, but will apply herbicide as a last resort to ensure grain quality (wild oats) and prevent bigger future populations (Canadian thistle, wild mustard).
- Pre-seeding tillage: physical removal of weeds germinated prior to seeding
- Competitive crop choice: clover understorey competes with weeds in barley crop
- Increased seeding rate: 2-row 'Conlin' barley is sown at a higher rate than conventional 6-row barley varieties
- Ploughing the green fallow clover prior to weed seed-set reduces weed pressure in subsequent barley crop.
Diseases
Barley disease is generally not a problem for Ian as the clover absorbs extra moisture under the barley crop, reducing the humidity and conditions for infection. However, the barley in field 3 in 2003 required an application of Tilt for leaf disease.
Insects
Ian is fortunate to require no insect control, and is aware of the abundance of ladybugs, bees and earthworms supported on the farm.
System Benefits
Economics
Reducing costs while maintaining or improving yields is Ian's main driver towards farming with fewer chemicals. Barley produced without synthetic fertilizer input following the clover green fallow has a much greater profit margin than the second barley crop or previous crops produced under the conventional system with no legume plough-down.
Environmental
Ian has noticed a marked improvement in soil quality since including green fallow in the rotation. He was able to work the fields much earlier than other farmers in the dry 2004 spring which paid off when snow delayed seeding further. Further the dry conditions of 2003 did not reduce the productivity of Ian's soils, which he attributes to increased organic matter levels which can store more moisture.
The combination of deep-rooted clover, ploughing and increased organic matter has also noticeably improved the soil structure so barley will now grow evenly across the field including previously compacted, unproductive areas near gates and headlands.
Social
For Ian this system requires less time input than repeated cultivation during a black summer fallow, but takes more time to plough in the heavy clover crop in summer. Ian notes that improving the soil is more important to him than the time input, although he appreciates reduced exposure to unnecessary chemicals.
In A Nutshell...
- Conventional tillage practices: fields cultivated and harrowed prior to seeding crops. Clover requires ploughing in green fallow year as there is too much biomass for discs to sufficiently incorporate it into soil.
- Soil fertility is tested annually, recommending no fertilizer application to barley following clover green fallow. Standard nutrient levels required in second barley crop.
- Barley yields approximately 85 bushels/acre.
- Producing quality feed barley is Ian's #1 priority and will therefore spray wild oats or leaf disease beyond economic thresholds.
Advice to other farmers interested in farming with fewer chemicals:
- Keeping records is essential to know the costs of production.
- Soil testing is necessary. Although an extra cost, it will pay for itself by preventing the use of unnecessary fertilizer.
This page created August 2004.