Zimbabwe Absurdity

We grow our seedlings in compartmentalized expanded polystyrene trays. The cells are filled with a growing medium, in this case coir pith, and a seed is placed in each cell and grown out to maturity. This can take as little as four weeks in summer for tomato seed or up to four months in the case of gum tree seedlings as seen above. A seedling is deemed mature when it can be pulled from the cell and the roots hold the medium in a plug which will remain intact until it can be planted into the field. It also needs to be tall enough to be planted easily and not so tall that the leaf area will tax the roots ability to take up enough water in what, for the plant, is a stressful transition. There are other criteria that need to be met such as hardness of the leaves but that’s getting boring.

Being made of polystyrene the trays are light and rigid, which makes them easy to handle. It also makes it easy for the plant to grow its roots into the polystyrene which makes the seedling difficult to pull out of the tray. New trays have a smooth surface which is difficult for the roots to penetrate but as the trays age their surface becomes pitted and the plants’ roots can penetrate the polystyrene. To reduce this effect we dip the trays in a solution of copper oxychloride and water soluble glue. This creates a localized toxicity in the tips of the roots which stops them growing into the polystyrene and serves to sterilize the tray. Mostly it’s effective but as the tray ages and the surface becomes rough the roots grow into it anyway. The buildup of copper over many uses of the tray also causes a more general toxicity in the plant which can manifest itself as leaf discolouration and poor growth.

This general toxicity is most evident in gum seedlings as discoloured leaves and poor tip growth though in other seedlings it manifests as a general lack of vigour. I have noticed this for some years and when new trays are bought there was a noticeable “new tray effect” which I couldn’t really nail down to anything specific.

The coir pith we use is a by-product of the coir industry in India and other Asian countries. It’s the cork material that’s left over when the fiber has been extracted for ropes and mats. It has no nutrients in it so all must be added in the form of various chemical fertilizers. Organic we are not. This means that there’s little space for error and small changes in the formula can have major effects. Fortunately most of the work in this type of horticulture has been done long ago, albeit on other media, so it’s not as hit-and-miss as it may sound. Unfortunately I have a tendency to fiddle to try and get just that little bit of extra performance out of the system.

So when the gum seedlings started to become discoloured some years ago I put it down to something I’d done to the fertilizer formula. Thinking that it was a phosphate toxicity I designed a simple experiment. I bought several new trays, made sure they weren’t dipped in copper, then mixed differing quantities of single superphosphate that we normally use into the coir pith and grew out the gum seedlings. They were all good seedlings including those that should have had toxicity symptoms and those that had no single superphosphate added at all. It was that “new tray effect” and I knew it had to be the copper dip.

In Zimbabwe trash recycling is not a vibrant industry. There is a large municipal dump that I drive past on the way to work with a large warehouse building on it with “RECYCLING PLANT” painted on the front. Whether any recycling actually happens there is unknown. It’s part owned by one of the President’s sons but that’s a topic for another blog post. The old polystyrene trays we use end up on this dump site and add to the general pollution. It bothers me but the alternative is to import plastic trays from South Africa and they are very expensive and would likely not be recycled either. So I buy more of the local trays when I have to.

The gum seedling in the above photo is a good one. Though still young it has good root development, good leaf colour and good growth. It’s a product of a new tray – part of a batch that I bought earlier this year to replace older trays that were causing the copper toxicity symptoms. I have been seeing a general malaise in the tomato seedlings we are growing in old trays and should really replace them too. But there’s a problem.

I lease part of a property that supports my landlady’s ornamental nursery, another tenant’s rose nursery and the landlady’s son’s container rental business. The remainder of the property, some 10ha, is not utilized largely because we are in a bad area for sub-surface water and the three boreholes would not support irrigated cropping of any sort.

The 400ha of land on the boundary of “our” land is owned by a politically connected person whom I will call G. She acquired the land some time ago and set about building a wall around it. This is not just any wall – 3m high it has, a reinforced concrete core, a course of bricks on either side, pillars every 4m and topped with cornicing. It’s 9km long (measured on Google Earth) and is estimated to have cost US$500 – US$600 per metre. At a minimum $45 million G has clout and access to capital. So it was not without concern that we waited to see if the wall would include “our” property. It stopped either side.

My landlady’s son decided that the best way to make the property less attractive to acquisition by G and her ilk would be to develop it. Half the property was duly sold to a development company for construction of high density housing on condition that they changed the title deed to “development” rather than “agricultural” which is less attractive to the likes of G.

This development means that I will lose about a third of my current capacity and access to two boreholes that provide the bulk of my water. Remaining viable in a business that relies on large turnover on low value items/seedlings is going to be a challenge. So do I invest in new trays?

I was initially told that I would have about two years use out of the current two boreholes and that was six months ago. My landlady has had another two drilled on the remaining property but they are not very prolific. Uncertain times but to throw in the towel now on the premise that my business will fail would be defeatist. Tomorrow I will place an order for 2,000 new trays.