: Conservation agriculture for soil moisture conservation and fertility management in semi-arid areas ï‚§ Minimal tillage ï‚§ Use of cover crops ï‚§ Intercropping ï‚§ Crop rotation | Natural Resource Management (Soil and Water Conservation)
ASALsare characterised by water scarcity due to erratic and unreliable rainfallpatterns and high evapotranspiration rates, and fragile soils characterised bylow organic matter content and general high infertility. Due to highpopulation, people are migrating to ASALs putting more pressure on the naturalresources. Conservation agriculture (CA) is a practice that aims to producehigh crop yields while reducing production costs and maintaining the soilfertility and conserving water.
ConservationAgriculture embraces three basic principles:
1) Minimalsoil disturbance: Theideal is to plant direct into the soil, without hoeing or ploughing. Tillage isreduced to ripping planting lines or making holes for planting with a hoe. Soiland water are conserved. CA helps mitigate sudden changes in temperature andrainfall due to climate change.
2) Keepthe soil covered as much as possible:Mulch, special cover crops and crop residues left on the field protect the soilfrom erosion and limit weed growth throughout the year. In conventional farmingpractices farmers remove and burn crop residues or mix them into the soil witha plough or hoe. As a consequence, the soil is left bare, and is thereforeeasily washed away by rain or blown away by wind.
3) Mixand rotate crops:Planting the same crop each season, as sometimes practised in conventionalfarming, is minimised by planting the right mix of crops in the same field, androtating crops from season to season. This breaks down survival andmultiplication cycles of pests, diseases and weeds, resulting in higher yieldsand maintenance of soil fertility.
Conservationagriculture can reduce soil erosion since the practice barely disturbs thesoil. CA helps conserve soil moisture through the mulching effect of covercrops or crop residues. CA has shown potential to contribute to sustainableintensive agriculture production under adverse climatic conditions. The KenyaAgricultural Research Institute (KARI), through the Conservation Agriculturefor Sustainable Agriculture and Rural Development in Southern and EasternAfrica (CASARD), together with its partner (Africa Conservation TillageNetwork) are promoting and testing CA in five districts in Kenya. Two of thefive districts, larger Laikipia and Mbeere districts lie predominantly betweenarid and semi-arid areas with an average of 650 mm of rainfall annually.
Scaling up approaches used
Users ofCA include: small-scale farm holders; input suppliers; and equipmentmanufacturers and importers. CA has been promoted mainly through the farmerfield school approach, field demonstrations, awareness-creation campaigns andfarmer-to farmer learning initiated through farmer exchange visits.
Thecritical for successful promotion and wider adoption of CA entail: 1) locallyavailable equipment that is easy to use; 2) good will from governments, e.g.putting mechanisms in place for crop and livestock insurance; 3) access toequitable produce markets; 4) access to information; 5) production risksharing, incentives and policy support; and 6) availing appropriate implements.
Challengesencountered in respect of further dissemination of CA are:
Â§ Difficulty changing mindset of farmers:Switching to CA involves a fundamental change in mindset. This means farmersmust drop their traditional practice of preparing the land with a hoe orplough, and instead rely on â€˜biological tillageâ€™ using plant roots and earthworms.
Â§ Management of crop residues: Normally,farmers keep livestock and grow crops and use crop residues as fodder, fencing,roofing and fuel. They are therefore unwilling to use crop residues as mulch.In many ASAL areas farmers commonly release animals on to fields after cropsare harvested, compromising the principle of ensuring soil is covered at alltimes. The animals trample the fields, compacting the soil. This results inreduced infiltration and in soil erosion.
Â§ Policy framework is lacking: All stakeholders,especially researchers, ministries of agriculture and NGOs, must play aproactive role in ensuring that policies are formulated and enforced.
Â§ Tools: Currently, the basic CA toolslike jab planters, zam wipes, animal drawn planters, etc. were imported fromBrazil and very few local manufacturers are available.
Â§ Declining labour force: The labour forceis declining due to out-migration, employment in other sectors, and malaria andHIV pandemics.
Â§ Poor infrastructure and support systemsfor physical and financial access to production inputs: Improved seeds,fertilisers, chemicals, water and machinery are scarce.
Â§ Weed management in the early days: Thisis because a key component of CA is zero or minimum tillage, which in the earlystages can mean more weeds, meaning that herbicides may be required.
Â§ Pest and disease control: Anothercomponent of CA is to leave crop residues, which might lead to build up ofdiseases or pests from a previous crop.
Â§ Maintenance of vegetative cover over alonger period of the year: This can be a challenge where land is limited.
Â§ Inadequate residue/mulch managementpractices.
Toaddress the above constraints, the following actions are recommended:
Â§ Promoting growing fodder crops to feedanimals should be promoted
Â§ Training farmers and field extensionofficers
Â§ Popularising the technology usingdemonstration farms, field visits and exposure tours, and farmer field school
Â§ Using farmer champions to act as goodexamples to others
Â§ Policy support from the government
Â§ Partnerships between different players
Â§ Promoting farmer-to-farmer extension
Â§ Training local manufacturing artisans onhow to prepare CA tools and link them to finance institutions to facilitateaccess to credit
Severallessons emerged about how to encourage many people to use CA:
Â§ CA has been promoted effectively usingfield demonstrations and awareness creation campaigns.
Â§ Capacity building and mass media supportthe campaign.
Â§ Incorporating CA in school and collegecurricula could improve uptake of the technology.
Nogender restrictions or biases have been recorded where CA has been practised.CA implements and practices are adaptable to both men and women. The technologyis actually more gender friendly, as it is less labour intensive than othertechnologies are.
1) Land preparation for CA
Land preparation for seeding or planting under CA involvesslashing or rolling the weeds, previous crop residues or cover crops orspraying herbicides to control weeds. Seeding is done directly through themulch. Crop residues are retained either completely or to a suitable amount toguarantee complete soil cover, and fertiliser and amendments are eitherbroadcast on the soil surface or applied during seeding.
2) Principles and procedures ofconservation agriculture
CA embraces three basic principles which are appliedsimultaneously in the field: minimum soil disturbance, permanent soil cover;and mixing and crop rotation. These are discussed below.
a) Minimum soil disturbance
Â§ Soilis disturbed as little as possible; herbicides are used to eliminate weeds.
Â§ Seedsare planted directly into the soil, without ploughing.
Â§ Plantingis done using simple hoes or inexpensive equipment such as jab planters oranimal/tractor drawn direct seeders. The equipment penetrates the soil cover,opens a seeding slot into which it places the seed.
Â§ Thesize of the seed slot and the associated movement of soil are kept to theabsolute minimum possible. Ideally, the seed slot is completely covered bymulch again after seeding and no loose soil is left visible on the surface.
Â§ Thisimproves soil structure and enables the soil to retain more moisture, evenduring the dry seasons. Where high sporadic rainfall occurs in ASALs (due toclimate change), CA is able to reduce soil erosion since the soil disturbanceis minimal.
Land is not directly ploughed
Manual direct seeder or jab planter seeder (planting and fertiliser application is done once)
Tractor-drawn direct seeder.
No-till or minimum using post-emergenceherbicide application followed by direct planting.
b) Permanent soil cover
Â§ Keepthe soil covered as much as possible.
Â§ Toachieve this, use special cover crops like Dolichos lablab, njahi, nzavi
Â§ Onecan also use crop residues left on the field to protect the soil from erosionand limit weed growth throughout the year. Where rain is scarce, CA conservesmoisture by mulching.
Do not burn crop residuals
Plant the crop along the contours and apply mulch to conserve moisture
NB: Using appropriate legume cover cropsreduces the need for external inputs like chemical fertiliser and herbicides.Cover crops need to be managed before planting the main crop. This can be donemanually or with animal or tractor power. Ensure that the soil is always keptcovered.