Managing Farm Plants
The foundation of every farm is it's plants; in some instances because the plants are producing crops for harvest, and in others because the plants are growing food for the livestock. Some factory farms may be able to rely less on growing plants, but even there, plants will grow as weeds, be planted to provide shade or wind protection, or be used for erosion control. There is no escaping plants on any sort of farm, and to manage plants properly, good or bad, the farmer needs to understand how plants grow, and appreciate the differences between different species.
Plants may be pasture species, fodder crops, grain, vegetables, fruit or other harvested plants.
SELECTION CRITERIA FOR PLANTS
- What crops are currently in demand? You need to attempt to gauge future demand, particularly if you are looking at growing crops that are long term investments and may take several or more years before they produce crops (e.g. vines, tree fruits, nuts). Look at the "stage" of a crop's demand as well. Is it a new, growing market, or is it one that everyone is "getting into" (resulting in a possible glut on the future market)? Select high demand crops where possible to remain economically sustainable.
- Which crops are suited to growing in your locality? Some alteration to the soil and climate of the area may be beneficial in the long term. Examples are the introduction of windbreaks to prevent erosion, installing irrigation systems, or the creation of a microclimate to encourage growth of a particularly suitable plant.
- What resources do you have to produce different crops? This could include suitable land, equipment, staff, materials, or the financial backing to obtain these. Investment in equipment and materials must also be balanced with the amount of return you can expect.
- What expertise or knowledge do you have with regard to growing different crops? Can you obtain that knowledge?
- For new or experimental crops, determine what information is available on their culture and find out what grower support exists (e.g. Department of Agriculture). Trying crops new to your area or still in an experimental usage stage can be costly, but have the potential to be very rewarding. Overseas research can often shed light on the suitability of the crop for your area. Start small and work up to larger production numbers if the results are good.
- How will the crop under consideration work with other crops? For instance, is their a market for a suitable companion plant? What crops should it be rotated with? What effects will this have on the soil and on the economics of growing this plant? Can the crop be marketed easily in conjunction with other crops you produce?
- What will you be using the crop for? If you are considering crops for your own subsistence, is this the cheapest and easiest way to obtain the crop? If you are using it for stock feed, is this the cheapest or easiest way to obtain suitable stock food?
Agronomic crops are most commonly grown as a broad acre monoculture; however, this way of farming has significant problems as well as obvious advantages.
Monoculture involves growing just one typeof plant and attempting to exclude all others. There is almost no diversity is present at all. Crops grown in this way are often especially open to attack from weed and pest species. Many predators return annually to these farms, assured of a continual food source. Stripping crop targeted nutrients from the soil is also a major problem in a monoculture. To combat these effects farmers are required to use greater quantities of chemicals in the form of weedicides, pesticides and fertilisers.
Classic examples of monoculture can be witnessed throughout continents such as Australia and North America where vast tracts, millions upon millions of hectares of land are used for wheat and other grain crops. The species being produced are generally fast growing, high yielding, hybrid varieties requiring considerable chemical inputs. They are often sterile varieties and seed must be purchased for each planting. The seed suppliers are often the same or sister operations to those that provide the required chemicals needed to protect the crops from insects and disease.
Aside from the problems of poor land management and heavy use of chemicals that the monoculture farm can create, the primary producer must remain viable. Quantity of production and most productive use of land can be heavily influenced by perceptions of economic viability.
There are examples of systems that are predominantly monoculture that are relatively successful in terms of sustainability. The reason for this is because the people who use these systems are aware of the dangers of monoculture, especially in terms of chemical use, and have therefore developed sustainable natural defensive measures.
One method that is employed is to plant species rich islands that are located centrally at intervals throughout the crop. These resource islands, which can be made up of literally hundreds of different indigenous plant species, seem to work quite effectively at controlling pest and disease populations as well as increasing soil fertility.
Research is still being conducted to assess to what degree these islands are successful but it would appear that the concept works. Further work on which alternative species are the most beneficial will help to ensure the resource islands are most effective. This concept is very similar to the permaculture ethic of companion planting although it exists on a far grander and perhaps greater diversity scale.
KEEP CHANGING THE CROPS
Many of the problems associated with monocultures can be minimised by simply rotating crops. As a general rule, when there are more problems, extend time periods between plantings of the same crop. Sustainability may be improved by the following:
- Grow a crop for half of the year, and graze the same land for the other half.
- Grow different crops on the farm, and rotate them so the same crop is not grown in the same paddock more than once every 2 to 3 years (or preferably longer).
- Fallow areas between crops (i.e. do not graze or grow a crop).
- Grow cover crops for green manure at least annually to revitalise the soil.
- Ley Farming Systems - this involves alternating cereal grain production with pasture. Annual medics or sub clover are useful in these systems, mixed with grasses, to produce high quality forage.
Row crops may include things such as maize, vegetables, cut flowers, herbs, and berries. They are often, but not always, replanted periodically. As such, the ground needs to be cultivated, and a "seed bed" prepared. Poor seed germination is the result if the soil is not prepared, yet cultivation, especially of large areas, can cause major problems with erosion.
The following techniques will not only help to control erosion, but also make row crops a desirable crop in a sustainable agriculture system. They include:
- Inter-planting temporary crops (e.g. vegetables and other annual plants), with permanent crops (e.g. fruit trees or vines). Another option is to grow grass or other ground stabilising ground covers between rows of permanent planted fruit trees, vines or flower crops (e.g. woody perennial flowers). Cover crops that can be tilled into the soil to enhance its properties are ideal in these situations, providing they are not competing too much with the main crop for soil and nutrients. Growing low growing legumes such as clover between rows can add valuable nitrogen to the soil.
- Restrict row crop length on steep slopes (perhaps to 70-80 metres in higher rainfall areas) to minimise run-off effects.
- Maintain a grass strip at the end of each row to catch run-off of water and soil particles.
- Use a large tine to deep rip areas where a tractor has worked (and caused compaction) to increase depth of water penetration.
- If using a plastic mulch is necessary (e.g. in strawberries), water run-off is increased, so areas between rows need to be planted (e.g. with rye grass, barley or clover). The second crop can be harvested or used as a soil enhancer.
A cover crop is simply a plant which is grown for the purpose of improving the condition of the soil it is grown in. It is most commonly ploughed in, but can also be cut and left to lay on the soil. The latter method is very slow, but can be effective. In theory a cover crop should increase organic content and fertility of the soil, but research has shown that this is not always the case. The real contribution of a cover crop is affected by:
- The amount of growth achieved.
- The plant varieties grown (e.g. legumes add more nitrogen to the soil than what they take out).
- Whether any part of the cover crop is harvested and removed from the paddock (perhaps as hay).
- Whether there is a strong leaching affect (e.g. in sandy soils or on steep slopes).
- Temperature and moisture conditions (excessive heat and moisture can result in rapid decay of organic material, and in fact little if any increase in soil organic content. Excessive dryness can result in very little decomposition).
- Carbon:Nitrogen ratios of residues (High ratios such as 100:1, are slow to decompose, but lower ratios may be much better).
- Soil life (the presence of certain micro organisms, worms, etc. can have a significant bearing upon decomposition, release of nutrients, and even mixing of residues into the soil mass).
A survey of farmers in north eastern USA found farmers were using cover crops for varying combinations of the following reasons:
- To improve soil fertility, soil structure or tilth.
- Control erosion.
- Reduce the need for fertiliser and other soil amendments.
- To increase nitrogen levels (i.e. legumes as a green manure).
- Improve nutrient availability.
- Minimise leaching.
- Weed, pest or disease control.
- Preparing land for production of other crops (e.g. vegetables or grain).
- As a livestock feed supplement.
The cover crops used must be matched with the desired outcome.
The following tips will help in determining selection of a cover crop:
Type of Crop. Perennial crops are generally preferred over annuals. With annuals, large populations of nematodes often move into the soil after maturing, causing problems for the root system of any subsequent plantings.
Effect on soil pH. Alkaline tolerant plants such as sorghum and barley, can be grown to reclaim alkaline (lime) soils. Growing a single crop of these plants may cause sufficient acidification to allow less lime tolerant legumes to be grown, further acidifying and allowing it to be used for livestock or a cash crop.
Timing. The crop should be incorporated (tilled) before maturity (ie. before flowers and seed forms)
Water use. While cover crops, like any other crops, do use water, their root growth can lead to better penetration of water into the soil. Additionally, residual organic material left by the plants will lead to increased water conservation.
Legume Cover Crops
Legumes often contain up to 30% more protein than grasses, giving them better food value for livestock. Another advantage of legumes as a cover crop is the production of rhizobium. Rhizobium is a bacteria which legumes can be inoculated with, resulting in production of hydronium ions in the soil. These ions in turn lower the soil pH, making the soil increasingly acidic.
The decomposition of organic residue also has an acidifying affect on soil. Increased organic matter does however buffer (i.e. sort of slow down) this acidification. Never the less, excessive and continual use of cover crops, especially legumes, without liming or use of a similar treatment, can result in soil becoming too acid, and losing productive capacity.
You can use pre-inoculated or pelleted seed, or you can inoculate seed yourself.
- Add the inoculant to another medium (e.g. peat mixed with water and gum arabic). Use 1 part sticking substance (e.g. gum arabic) to 10 parts water. Other sticking materials that can be used include corn syrup, sugar, powdered milk or various commercial stickers.
- It is critical to use only fresh inoculant in the appropriate concentration.
- Use the appropriate rhizobium for the legume being grown. Keep in mind that rhizobia perform better on some legumes,(e.g.alfalfa) when seed is coated with Calcium Carbonate, while others perform better when left uncoated (e.g. red clover).
- Check expiry date. Commercially produced, pelleted seed should be sown as soon as possible, at least within 4 weeks of production as it does not store well.
- Always store inoculant in cool,dark place.
- In dry conditions, inoculant rate may need to be doubled.
- If legumes exhibit yellowing of foliage, this may indicate nitrogen deficiency resulting from failure of the inoculant.
- Applying some nitrogenous fertiliser when planting a cover crop may actually enhance the nitrogen fixation of the legumes (e.g. around 30 kg per hectare of starter nitrogen).
- Generally soil pH needs to be over 5.5 for rhizobium to survive.
Shade Tolerant Cover Crops
These include Cowpea, Burr medic, Hyacinth Bean.
Salt Tolerant Cover Crops
Strawberry Clover, White Clover, Burr Medic, Field Pea, Barley 'Salina', are all ideal for use in areas of high salination or heavy salt spray.
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