An overview of mechanisation in organic crop production

Some of the basic field level operations in organic agriculture which have a significant bearing on labour and would benefit from mechanisation are outlined in this section and discussed in more detail and with examples in subsequent sections. These include:

1. Making compost, especially for larger-scale production
2. Practicing minimum tillage to maintain healthy soils
3. Fertilising – applying organic materials (compost, well-rotted manure, etc.)
4. Managing green manures and soil cover crops
5. Planting into covered soil or minimally tilled soil with proper equipment
6. Timely and effective weed management
7. Primary processing of small grain cereals including maize

Organic farmers fertilise their soil with well-rotted farmyard manures and compost rather than commercial synthetic fertilisers. Successful organic producers understand that feeding their soils before and after every planting is the key to sustainable production. The objective of fertilising in organic farming is to feed the plants and soils together unlike some synthetic fertilisers which aim to provide nutrients to the crop only. Farmers can benefit from equipment that helps with the process of making these natural fertilisers, e. g. for composting as discussed already in previous sections, and in applying the organic fertilisers to the fields.

Mechanisation can promote and maintain soil health by reducing soil disturbance and tillage in both seedbed preparation and weeding operations. Organic farmers transitioning from conventional to organic agriculture may start by using a plough if it is the equipment they currently have. Still, over time, they are encouraged to transition to minimum/conservation or no-till practices such as skim ploughing, direct seeding, and minimum tillage weeding equipment which reduce damage to the soil and help to preserve organic matter.

Healthy soils are key for healthy crops. Frequent intensive tillage with a mouldboard plough can degrade soil quality and health over time. Ploughing loosens the soil and buries crop residues. The loosened soil allows air to enter into the soil rapidly and this results in an acceleration of the breakdown and loss of humus from the soil. The close mixing of crop residues, moisture, oxygen (in air), and microorganisms during ploughing speeds the decay of new organic matter and its loss from soils. On the other hand, low disturbance or minimum tillage leaves crop residues in the top few inches of soil where it improves infiltration of rainfall or irrigation water, reduces evaporation of water from the soil, reduces soil crusting and erosion by water or wind, and releases crop nutrients into the root zone.

• Deep/conventional tillage: Use of a plough or other implement that works at a soil depth of up to 25 cm and inverts the soil completely.
• Minimum/conservation tillage: Tillage using a variety of implements that work at a relatively shallow depth (generally less than 10 cm) and do not lead to complete inversion of soil.
• No tillage: A method of farming where soil is not routinely tilled and crops are seeded directly using hand-held, animal-drawn or motorised implements. The planting holes or furrows are prepared by cutting through crimped green manures or dead plant residue on the soil surface.

The type of equipment used can also have a significant effect on soil health. As well as promoting minimum tillage, organic agriculture also focuses on reducing practices that can lead to soil compaction. Soil compaction can be caused by many processes, including farm operations. For example, heavy farm equipment can cause soils to compact if repeatedly used on fields without a remedial strategy to the compaction. Other common causes of compaction besides heavy equipment include heavy rainfall, e. g. on bare soil or freshly ploughed fields, some irrigation methods, and other factors. The use of heavy equipment such as tractors is a major contributor to soil compaction. Therefore, if tractors are used, minimum/conservation tillage or no-tillage options can help to avoid soil compaction by limiting the number of passes by the tractor over the field. However, the weight of more complicated machinery such as the direct seeders used in no-till agriculture must be balanced with the benefits of the no-till method.

As far as possible, organic farmers are encouraged to use reduced tillage as described in more detail in later sections of the training manual.

Green manuring is one of the key strategies towards soil fertility management in organic farming. Green manure plants such as velvet beans (Mucuna species) Dolichos beans, Sunnhemp, Cowpea and others are grown and, before flowering, are ploughed under to mix them with the soil in order to improve the physical structure and fertility of the soil while providing nutrients to the subsequent crop. Further, organic farmers aim to keep soils covered as much as possible during and between growing seasons. The farmers understand that keeping their soil covered preserves moisture, prevents erosion from rain and wind, and promotes healthy soils. Between growing seasons, they may use cover crops, green manures, and intercropping and/or mulching during the growing season. To manage the green manures and cover crops in organic farming where reduced soil disturbance is observed, the farmers can use equipment which cuts and turns these plants or crops into a mulch layer that protects their soil, adds nutrients back to the soil, and suppresses weeds.

When farmers reduce tillage intensity, planting equipment requirements will also change to a large extent, in particular for the animal draught-powered and motorised systems. The farmers will need to use implements which enable them to plant in fields prepared with minimum or no tillage equipment. Also, when cover crops or mulches are left on the fields, the farmers should use equipment that can help them easily and accurately penetrate and plant through these soil covers and plant mulches. Tools and implements such as a hoe with a long blade, a jab planter, or no-till planters (motorised and animal powered) are essential to the farmer for successful planting and seedling emergence.

Weed control is one of the main challenges faced by organic farmers. Organic farmers understand that weed control requires more effective planning and earlier, more targeted weeding practices with the right equipment to achieve good results. They use hand-held tools and mechanical cultivation as well as preventive measures such as crop rotation and mulching to control the weeds. Mechani­cal cultivation can involve different weeding tools dependent on the type of crop and the stage of crop growth. Therefore, the farmers prioritise equipment that can help maximise results while minimising time and effort.

Harvesting, cleaning and processing arable field crops is tedious for many smallholder farmers. In particular, the harvesting of small grains such as millets and sorghum, and their subsequent primary processing, i.e. threshing, shelling and dehulling, can consume time and energy from smallholder farmers. Sometimes farmers spend considerable amounts of money to hire labour in order to harvest crops timely before they become spoiled from weather elements, or by pests and diseases. Mechanising these operations can improve their production and utilisation due to reduced strenuous work.