Agricultural systems that integrate crops and livestock offer benefits for sustainability, resilience, and economic diversity. Beyond the influences on ecological processes and soil microbial communities, the opportunity to utilize manure, crop residues (i.e. wheat straw for bedding), and crop rotations around feed production contribute to a more nutritious livestock feed production and promotes environmental stability from an improved whole-farm nutrient balance.
The nutrient balance in mixed crop and livestock systems is shaped by the production of livestock feed on the crop acres. Livestock have specific nutrient requirements which results in crop production practices that focus on quality of feed as opposed to highest yield. For example, forages are harvested to match livestock nutrient needs for energy or protein based on the livestock type, stage of production and end goals and purpose of the livestock being fed (e.g., milk, meat, eggs, reproduction). It is important for crop producers without livestock to consider end markets for crops and nutritional quality.
Every field producing crops has unique and site-specific characteristics that influence management, inputs, and profitability. Integrated crop management takes all aspects of crop production into consideration.
It starts with a healthy soil
Soil health is described as the soil’s capacity to support crop growth without becoming degraded or otherwise harming the environment. Physical, chemical and biological indicators can help determine relative soil health. Physical indicators include aggregate stability, available water holding capacity, soil structure and soil compaction. Chemical indicators include soil pH, and soil nutrient content. Biological indicators include soil organic matter/soil organic carbon, microbial respiration, soil life populations. A healthy soil will:
- have good structure, minimal compaction and can resist crusting.
- have good drainage, water movement and water-holding capacity.
- have nutrient levels, pH and organic matter in the optimal range for crop production.
- be resistant to wind, water or tillage erosion.
- produce uniform crops growth with uniform seedling emergence and root growth.
- have an abundance of soil life and microbial activity.
- readily decompose crop residue.
Most of the characteristics of a healthy soil have a direct or indirect link to other aspects of crop management.
Crop Rotation
Crop rotation is an integral part of the crop production system. A well-planned crop rotation will:
- increase yields.
- aid in maintaining soil organic matter levels.
- protect against soil erosion.
- improve resilience against weather extremes.
- help to disrupt insect, disease and weed cycles.
- provide residual nitrogen from legumes in the rotation.
- spread workload, labour and equipment logistics.
The basic rule of crop rotation is that a crop should never follow itself. Continuous cropping of any crop will increase the buildup of diseases and insects specific to that crop and will potentially result in heavier infestations and reduced yields.
The greatest benefit from crop rotation comes when crops, including cover crops, grown in sequence are from different families; monocots (grasses) and dicots (broadleaves). The fibrous root systems of cereal and forage crops (including red clover) are excellent for building soil structure and helping to prevent compaction. The advantage of including wheat in the rotation often goes beyond the wheat year. Table 1-1 management consideration for various crop rotations provides an example of response to a crop following various crops in a rotation.
Table 1-1. Management Consideration for Various Crop Rotations
| Crop | Previous Crop | |||||
| Corn | Soybeans | Cereals | Forages | Edible Beans | Canola | |
| Corn | high residue volume to manageyield depressionless herbicide rotation/weed control optionscorn rootworm slugs (in short term no-till) | greater herbicide rotation/weed control optionsincreased European chafer risk (light-textured soils) | high residue in no-till system if straw wasn’t removed could keep soils coolergreater herbicide rotation/weed control optionsgreater cover crop options | increased wireworm risk in grassy sod | no issues | reduced mycorrhizae = less P uptakepotential reduced crop growth |
| Soybeans | high residue volume to managegreater herbicide rotation/weed control optionsslugs (short term no-till) | yield depressionlow residue return – declining soil organic matterless herbicide rotation/weed control optionsincreased risk of soybean root diseases, white mould, soybean cyst nematode, | herbicide rotation optionsslugs could be issue (over-winter cover) | increased wireworm risk | increased risk of white mouldsoil degradation | increased risk of white mouldpotential reduced crop growth |
| Winter Cereals | increased Fusarium head blight risk | planting date issues depending on length of season bean variety | increased risk of seedling, root and leaf diseasesreduced herbicide rotation/options | increased risk of wireworm feeding | earlier harvest makes timely planting easier | may cause a slight reduction in growth |
| Spring Cereals | high residue can affect seedbed preparation | no issues | increased risk of seedling, root and leaf diseases | increased risk of wireworm | no issues | no issues |
| Forages | high residue can affect seedbed preparation | limited weed control optionspotential for herbicide carryover | limited weed control options | autotoxicity if re-seeded too soonlimited weed control options | no issues | no issues |
| Dry Edible Beans | no issue | increased risk of root rots, white mould | slugs may cause damage in no-till | slugs in no-tillreduced herbicide options | soil degradationincreased root rotsincreased white mould yield depression | white mouldmay cause a slight decrease in growth |
| Canola | slugs may cause damage in no-tillharvest is too late for planting winter canolapotential for herbicide carryover | increased risk of root rots, white mould | no issues | slugs may reduce stand | increased risk of white mould | yield depressionincreased root rotsincreased white moulddecreased soil structure |
Most of the characteristics of a healthy soil have a direct or indirect link to other aspects of crop management.
Rotation Economics
The success of a crop is generally evaluated on economic yield, where inputs and fixed costs are subtracted from gross profit. Most of the time the crop is evaluated on a per year basis and the decision as to which crop to grow includes market demand as part of the decision-making process. A more sustainable approach to crop economics would look at economic yield by rotation. This would combine inputs and fixed costs for all the crops within a crop rotation, dived by the gross profit of all the crops within that rotation. This would allow a longer-term evaluation of all the crops and could often reflect benefits beyond the actual crop harvested, such as pest management, herbicide rotation opportunities, manure application to fit soils or soil building practices.
Economic Justification for Including Wheat in a Corn-Soybean Rotation2
An example updated from Dr. B Deen U of Guelph
Putting the economics to a three crop rotation in Ontario
6.5 bu/acre @ $5.50/bu = $35.75
- 9%–14% increase in soybean yield
5 bu/acre @ $13.25/bu = $66.25
- reduction in nitrogen requirement
26.4 lb/acre @ $0.75/lb = $19.80
- other advantages
- tillage reduction
- yield stability
- opportunity to sell straw
- potential reduction in compaction
- improved soil structure
- spread-out workload
Conservative estimate = $10.00
Total additional profit to wheat is approximately $130.00/acre
Benefits of diversifying a crop rotation include:
- increased subsequent corn yield (average 4%)
- increased subsequent soybean yield (average 11%)
- opportunity for addition of cover crops
- opportunity for manure application
- opportunity for wheat straw sales
- spreading workload over growing season
When profitability is assessed on a full rotation basis, often the economies of scale have resulted in accepting a lower profit per acre.
2Source: Dr. B. Deen, University of Guelph.
Integrating Cover Crops into the Rotation
Resilient crop yields can be maximized by improving soil health, which is enhanced with cover crops. Long-term advocates have found that adding cover crops to their rotation adds a critical amount of additional carbon to the soil.
Cover crops should be considered as part of the overall crop rotation, and especially on soils with lower organic matter, or on fields with short rotations and little return of crop residue or manure.
Cover crops can provide multiple benefits to the soil. Cover crop species selection will depend on the goal or expected benefit from a cover crop. Matching cover crop choices to function lists some of the reasons for including cover crops in a rotation and lists the potential cover crops that best meet these goals. (More detailed information can be found in the Soil Management section)
Table 2. Matching Cover Crop Choices to Function
| Cover Crop Function | Cover Crop Options |
| nitrogen production | legumes – red clover and other clovers, alfalfa, peas, vetch |
| nitrogen scavenging | fall uptake – daikon radish and other brassicas, oats, barleywinter/spring uptake – cereal rye, winter wheat |
| weed suppression | fast growing/shading plants –brassicas (i.e. diakon radish), winter rye, buckwheat |
| building soil structure | fibrous root systems – oat, barley, rye, wheat, triticale, ryegrass or clovers |
| reducing compaction | most cover crops will assist in reducing compactionmoderate compaction – diakon (oilseed) radish more severe compaction requires strong, dense tap roots over time – alfalfa, sweet clover |
| biomass return to soil | fall seeded – spring cereals, diakon radishsummer-seeded – millets, sorghum, sudangrass, sorghum-sudan grass |
| erosion protection (wind, water) | most cover crops, once established – winter rye, winter wheat, spring cereals (seeded early) |
| emergency forage | fall – oat, barley, wheat, rye, forage brassicas (turnips)summer – millet, sorghum, sudangrass, sorghum-sudangrass, |
| livestock grazing | |
| nematode suppression | cutlass mustard, sudans/sorghums (Sordan 79, Trudan 8) pearl millet (CRPM 101), marigold (Crackerjack, Creole), oilseed radish (Adagio, Colonel)Not all cover crops have the ability to suppress nematode populations; some can act as hosts. Cover crop activity is variety and nematode-specific |