Developments in Crop Husbandry Practices for Sustainable Maize Production

✅ Paper Type: Free Essay	✅ Subject: Environmental Sciences
✅ Wordcount: 2799 words	✅ Published: 23rd Sep 2019

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Title 2: ‘Developments in crop husbandry practices for sustainable maize production’

The requirement to feed a rapidly growing Zambian population has never been higher with maize production holding the key. Maize is the staple food in Zambia and therefore the most important farm product. The country’s staple dish is nshima which is a thick porridge made from finely ground corn meal.

There are two categories of farmers in Zambia which are commercial and subsistence. Commercial famers largely grow export and cash crops whereas subsistence farmers grow staple crops. Subsistence farmers grow most of the commercial maize for the country and thus, are the farmers that food security is most dependant on. As a result, sustainable farming practices and the developments pf these practices for these small-scale farmers are key to ensuring the future of food security of the country.

Conservation Agriculture

According to Conservation Farming Unit (CFU), Conservation Agriculture is generally defined as a ‘management system based on three principles that should be applied in unison in a mutually reinforcing manner: minimum physical soil disturbance, permanent soil cover with live or dead plant material (e.g crop residues), and crop diversification’ (“About Conservation Farming”, 2018).

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With droughts and climate change affecting food security, Zambian subsistence farmers must be innovative. One way that allows these farmers to be innovative and produce maize and other crops sustainably at the same time is through this world-wide adopted methodology of conservation agriculture, or commonly known in Zambia by the locals as conservation farming.

Conservation agriculture originated in 1930s America when the infamous ‘Dust Bowl’ caused wide spread devastation of arable land across the Mid-West as a direct result of soils being exposed to erosion because of conventional tillage techniques (Derpsch, 1996). This was much the same case in Zambia. The country’s agriculture was going into the 1990’s with land quality and productivity declining at a significant rate. A major review of the situation that Zambian agriculture faced stated that, ‘The underlying causes relate to inappropriate farming practices, excessive erosion, increasing levels of fertilizer-induced acidity and soil compaction due to excessive and repeated cultivation.’ (IER 1999). As a result, the Zambian National Farmers Union (ZNFU) became a driving force in implementing appropriate minimum tillage package for large scale, mechanized farming (commercial) as well as smallholder hand hoe farmers (subsistence) and in 1995, the hand hoe analogue of minimum tillage systems was introduced (Haggblade & Tembo, 2003). Since then, crop husbandry practices for conservation agriculture have been adapted, developed and improved to suit the Zambian subsistence farmers to give them the best chance of producing high yields as well as utilize the soil in a sustainable manner.

The aim of conservation agriculture has been to improve rural livelihoods through sustainable intensification of crop production.

Site selection

The first aspect that a farmer has to consider when planting a crop of maize, is what site he is going to select to plant his/her crop. This is done based on a knowledge of the soil conditions, weather patterns and crop rotations.

As mentioned, one of the three principles of conservation agriculture is crop diversification (crop rotations). Finding which crops are best to rotate is critical when it comes to optimising yield which is an aspect that has been researched and developed over the years. In Zambia, subsistence farmers usually rotate maize, followed by legumes such as soya beans or ground nuts and in the following season a cash crop such as cotton. As a result of good rotation practices, crop production is ensured, the system becomes more climate resilient and more carbon is stored in the ground (World Bank Institute & TerrAfrica, 2017).

Another important aspect of site selection is weather patterns. According to a recent article, having access to information about when and how long it will rain for is proving to be the difference between success and failure for some smallholder farmers in Southern Zambia. Although farmers practicing good conservation agriculture may be more safeguarded to the adverse effects of the harsh droughts that can strike the country at any time, having access to this information can greatly help. This is a big development for these famers as planting maize at the correct time can increase yields and as access to this information becomes more readily available and accurate, these farmers will continue to benefit (Phiri, 2018).

Crop establishment

After the farmer has selected the site where he is going to plant his/her maize, the establishment of the crop becomes the next point of focus. Seed bed preparation, timing, moisture in the soil, grains planted per unit area and depth of planting are all critically important when it comes to getting the seed to germinate and establish itself.

Seed bed preparation is fundamental in conservation agriculture. One of the main problems that face subsistence farmers that use conventional tillage techniques is that they often need to get land ploughed by a contractor as they do not have the machinery or man power on hand to create the soil disturbance desired. By the time the plough has reached them in the remote areas it is often too late, and the early moisture required in the soil for germination and good yield has been lost costing the farmer a lot of unnecessary time and money. As per conservation agriculture’s three principles, there must be minimum physical soil disturbance, and this is achieved through minimum or zero till. In the case of most of the farmers, seed bed preparation has to be done without mechanization. Minimum tillage without mechanization can either be done by hand hoeing otherwise known as the min-till basin method or ripping and zero till without mechanization can be achieved by direct drilling.

The min-till basin method uses a long bladed self-sharpening Chaka hoe to dig basins that are 20 centimetres deep and 30 centimetres long before the rains. After the basins are dug, accurate measurements of basal fertilizers, lime and manure are applied. The basin is then backfilled to 5 centimetres from the surface. After the first rains, seeds are hand planted into each basin and covered immediately while there is still enough moisture to ensure emergence. With the development of this method, more farmers are starting to realise the vast benefits which include ‘earlier planting, more even and optimal plant populations, less re-seeding, reduced erosion if sufficient residues present, reduced crop stress during dry spells, more precise and timely application of nutrients, reduced labour inputs and higher yields.’ The images below are taken from the NFU’s handbook, ‘The practice of Conventional and Conservation Agriculture in East and Southern Africa’ and illustrate the process of the min till basin method.

Fig. 1

Step 1: Basins dug 20cm deep and 30cm long

Fig. 2

Step 2: Accurate application of manure, fertilizer, lime etc.

Fig. 3

Step 3: Backfill to 5cm from surface. Implement used in image is a Chaka hoe

Fig. 4

Step 4: Seeds are hand planted after first rains

The second method to achieve minimum till is by ripping using namely the ox-drawn Magoye ripper which was developed at the Ministry of Agriculture’s research station in Magoye, Zambia. It was tested locally at the Golden Valley Agricultural Research Trust (GART) and because of its success, it is produced and exported to surrounding countries in Eastern and Southern Africa. Ripping usually occurs in the dry season. Although soil is still being inverted, using the Magoye ripper reduces this surface soil disturbance from 100% (conventional tillage) to 10%. The farmer must also make sure that the rip lines are always the same from season to season to ensure sustained minimum soil disturbance. However, using this method does have its drawbacks. Ripping 1 hectare using an ox-drawn ripper can take up to 4 hours and the cost of hiring oxen is about $30 per hectare and essential training on correct set up is required. By using this method, the farmers allow themselves the benefit of planting early and retaining that very important early moisture in the soil which, once again, results in better guaranteed emergence, establishment and good yields.

Fig. 5

The ox-drawn Magoye ripper

Fig. 6

Dry season ripping using the Magoye ripper

The last method is zero till and this is achieved by using man powered zero till planters. In Brazil and Southern Africa, several companies have manufactured and developed these zero till planters with configurations that are suited for oxen, horses and donkeys. This method has the same drawbacks as the min-till ripping described in the previous paragraph with regards to the farmer having to hire oxen, receive thorough practical training to operate the planter, buy the machine and maintain it. Soil is still being inverted but using zero till planters reduces soil surface disturbance to less than 5% which is hugely beneficial as it increases microbe activity in the soil therefore increasing the soils organic matter content. A machine such as the Fitarelli zero till planter is also very efficient as it takes only one pass to plant and fertilize. By disturbing the least soil, it is the most sustainable method and ensures that the soil can be productive for many more years.

Fig. 7

The ox-drawn Fitarelli zero till planter equipped with fertilizer hopper to increase planting efficiency.

Crop protection

Once the crop has been successfully established, making sure it is protected until harvest becomes an important focal point for the farmer. The biggest challenge that faces smallholder farmers when it comes to protecting their crops are weeds which cause a major threat to the sustainability of conservation agriculture. There are two methods of weed management that these farmers can adopt while practicing conservation farming: weed hoeing done by hand and herbicides. Weed control by hoeing usually takes place post-planting as soon as weeds start to emerge and is carried out 2-3 times per season. This is because farmers practicing conservation farming are expected to keep their fields weed free. Weeding is labour intensive, and many farmers indicate that this is when labour peaks occur (Mazvimavi, Ndlovu, Nyathi & Minde, 2010).

The other method of weed management that smallholder farmers can use is herbicide applications. There are many different herbicides that can be applied to weeds in a maize field with glyphosate being the most prominent.

Crop nutrition

Feeding the crop once it has established is another very important focal point for the farmer. Most smallholder farmers in Zambia use fertilizer or manure to make sure that the crop is receiving the right amount of nutrients.

Fertilizer is applied twice per season by farmers practicing conservation agriculture which is a basal fertilizer and a top dressing. As recommended by the CFU, for farmers adopting the min-till basin method, a precise measurement of 8 grams using a No. 8 cup of basal fertilizer should be scattered at the bottom of each basin 2 months before planting for whereas farmers who have ripped their soils should scatter a 100ml jar over 10 to 20 paces of furrow depending on the soil nutrition. Top dressing is applied when the maize is roughly knee height. Farmers are encouraged to use 6 grams of top-dressing fertilizer measured using a No.8 cup which is put into a small furrow alongside each plant. Both applications are very

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