The Commonwealth Partnership for Technology Management, CPTM, is a not-for-profit membership organisation, established in 1995, to help the Commonwealth member nations become leading agents in economic advancement through the sound management of technology and innovation via public/private sector partnerships. One such partnership was established in 2024 with the Zambian registered Global Grains.

Global Grains is actively directed by Stewart Parkes, a fourth generation farmer from a family with a rich history in agriculture, research, and contribution. Stewart’s work with several companies over many years has equipped him with knowledge and experience, both of which he brings to this partnership, adding great value. The CPTM-Global Grains partnership came about by virtue of a shared objective – to improve food security in the region via small-scale farming development – and thus the maize trials in question were born. Small-holder farming in Zambia and much of Southern Africa is operating at a remarkably low return, which makes the people in these countries vulnerable to food crises and stress events.

This trial will focus on the influence of liming, the benefit of using conservation farming practices, and the improvement of returns on investment. This investigation is carried out in the hope that we may expose the people of Zambia and further afield to a more sustainable farming practice that can better tolerate sub-optimal conditions, and ensure a greater sense of food security, regardless of each season’s challenges.

In order to develop a well-rounded, well-representative set of results, we established trial plots at four different sites. Two of these sites are on commercial farms in Mkushi, one is on a commercial farm in Mpongwe, and the last is on small-scale land in Katuba Village, Mkushi. The commercial sites each consist of five main plots outlined as follows:

Figure 1. Summary of plots at each trial site

The first objective was to demonstrate the effects of pre-liming and conservation farming practice. The application of agricultural lime serves more than one singular purpose. While the soils of our region have inherently low pH, the most obvious effect may be correction of acidic soils. This is true, however, it is the tip of the iceberg. When liming soils, pH is raised by removal of hydrogen ions, which are characteristic of acidity. When these hydrogen ions are removed, the soil becomes less acidic but it also frees up cation binding sites.

In this way we begin to influence cation exchange capacity, C.E.C., which is a measure of a soil’s ability to hold and exchange positively charged elements called cations, and so can be used to evaluate a soil’s fertility and its capacity to provide nutrients for plants. Liming also improves soil structure by increasing porosity and aggregation, it can improve solubility of nutrients, it can leach salts, and influence the Calcium:Magnesium ratio.

As the world’s population grows, and fertile land becomes allocated to living space and urban development, the matter of feeding this population is increasingly important to secure. Farming, which has never been for the feint of heart, is uniquely challenged every season with more intense weather and less predictable patterns. It is necessary to popularise methods of farming that both work to conserve our taxed soils and to fortify our crops against extreme stress events. Conservation farming, in the context of this trial, focuses on minimum tillage, zero burning, mulching for moisture retention, and reducing the area a farmer cultivates in order to maximise his efforts and resources.

Figure 2. Trial team pre-liming

Plot 1 was set up as our control, as a maize plot cultivated according to the norms of traditional practice. Standard inputs were used, with a medium maturing seed variety, PAN 53, the basal 10:20:10 D compound fertiliser, and the top dressing urea. In Plot 2, we used identical inputs, with the only difference coming in with an application of lime to each planting station before sowing of the crop. This lime was applied at a rate of 500kg/Ha. In Plot 3, we closely followed the guidelines of conservation farming laid out by Foundations for Farming, while making use of the inputs outlined above. We applied lime to each planting station alongside the basal fertiliser compound D, spaced planting stations 75cm x 60cm, and followed sowing of the maize seeds with a full cover mulch of the entire plot.

The next two plots trialled different inputs, still under conservation farming guidelines: Plot 4 maintained the standard seed variety PAN53, but made use of an organic, compost-based fertiliser, Albida Biofert, as the basal instead of compound D. The seed was also coated with a microbiological seed dressing of mycorrhizae and bacillus before planting.

The objective behind this plot was to use inputs to benefit our soils as much as our crop and, with this benefit to soil, lower the expenses of production, thus improving return on investment. Plot 5 was cultivated according to the commercial guidelines of Stewart Parkes, relying on his years of experience and tested maize production program. We used the Pannar seed variety PAN7M-83, we used the compound basal fertiliser WVC instead of Compound D, and we included applications of ammonium sulphate, muriate of potassium, and urea in top dressings. The plot was still pre-limed, spaced, and mulched according to the conservation method of farming.

Although the costs of production using a program like this are higher, the plot serves to demonstrate that with better quality inputs, better yields are achievable, and so return on investment and profit margin are still improved.
In Katuba Village, Joyce Changwe made some of her land available on which we were to establish three plots – one using standard inputs and conventional techniques, one incorporating a lime application before planting, and the last making use of our ideal inputs and conservation farming techniques.

From an early stage, we began to notice differences between our plots. All germinated with a similar success rate, averaged out to around 80%, with moderately consistent rainfall at all sites. This rainfall became more scarce and a dry spell hit our plots shortly after establishment, which is where things became interesting. The maize certainly showed the effects of this shortage of moisture, particularly those plots with no mulch at all. The Albida plots with their added benefits of soil biology seemed to fare the best in the severe weather, not wilting as noticeably as the others did. Although these conditions are characteristic of the region, accustomed to scorching hot days experienced between rain showers, they are no less taxing.

Figure 3. Maize plants removed from each plot 1-5 (left-right) in order to assess root development.

We progressed through our programs, applying a necessary insecticide, the first top dressing on the ideal plots, we thinned the plots out to an average of two plants per hole, and we applied our first urea top dressing to the ‘Standard Inputs’ plots. In the case of Plot 4, we combined the previously used Albida Biofert with urea, in a ratio of 70:30 respectively, again taking the opportunity to supplement soil biology and lower costs of production. Pictures and videos of the plots and how they were progressing through their growth stages were taken at very regular intervals, as well as some recordings of health parameters.

Figure 4. Picture showing height differences of plots, with Plot 5 closest.

Farming is never a simple and easy affair, so whilst following our outlined programs, we have taken measures and made applications to manage the specific challenges of this particular season. One such challenge has been with termites, which we have sprayed against multiple times.

Admittedly, the occurrence of termites is more likely with a thick ground cover of non-living mulch, so we make our recommendation to include mulching as a technique of conservation farming along with a recommendation to include a termicide spray of a product such as Fipronil. It should also be understood that the benefits of mulching are reaped to an extent, regardless of the thickness of the mulch layer or the thoroughness of ground cover. Simply laying down the stalks of the previous season and ensuring they are not burned can provide an element of moisture retention and stress management that may prove vital in a drought year.

Figure 5. Maize plot mulched with previous season’s stover.

With a few months left to this 2024/2025 growing season, we eagerly await the most respected and weighted parameter of an agricultural trial – yield. The yield data will be collected when the cobs have filled and matured, which will give us factual numbers to work with when calculating profit margins and overall successes of each plot. A close record has been maintained of actual costs of production per plot, which will be the basis of ‘input expenses’.

Although practice and inputs have varied, the chemical programs have been replicated across all plots, so that no discrepancies should arise due to better or lesser pest or disease control. The costs of these chemical applications are included in the cost of production, although they are the same for every plot at $26,67 and $407,05/Ha.

Figure 6. Costs of production.

Through our work and results so far, we believe our demonstration has been able to highlight some key points:

– Liming can improve pH, C.E.C., nutrient solubility and availability.

– Conservation practices of minimum tillage, zero burning, and smaller cultivation areas, can make extreme differences and cost nothing at all, meaning that this practice is accessible to any and every farmer in the region, regardless of scale, experience, or financial security.

– Taking opportunities to apply microbiological products can relieve the intensity of heat and water stress, and ensure our practices are sustainable. Using biology to take care of our soils helps to ensure healthy enough agricultural ground for generational production.

– Incurring greater costs of production by purchasing high quality, reliable products that are suitable to the area creates the opportunity to increase yields far above average and earn returns to cover these increased costs as well as bigger profits.

While a lot of information is available through this demonstration, it is important to reiterate the original objective – improving food security in the region through higher maize yields. Equally important is to remember that food security lies in the hands of small scale production, and we can make improvements to this production purely with education, awareness, and implementation of sustainable, conservative farming practices. Once we establish a basis of successful farming practices, the door of opportunity opens and the products and resources we use begin to make a bigger difference.