Mid March 2017
Our elevated valley adjacent to the old growth Kauri forests of Waipoua and Trounson has its own pattern of rainfall, sometimes distinct from the wider region. Dargaville, a thirty-minute drive Southward, is back to ‘drying out’, while here it is still raining on and off, with some heavy rainfalls. At this mid-summer time of year, the return on effort put into gardening is so much higher than at other times of the year, so I’ve been out in the rain digging potatoes, planting kale and harvesting cucumbers.
As well as wet, the weather has been unusually warm, which is great for vegetable growth, but is uncomfortable to work in, especially clothed in full rain gear. So, to cool off I dove into the river multiple times, which was elevated by rainfall and coloured brown by the topsoil eroding off the neighbouring farms. Most likely the river was also carrying away synthetic nitrates and phosphates applied to farm pasture, and probably manure from the livestock trampling the riparian zone next to the river. None of that did my health any good, as I developed and ear infection after a day or two of intermittent swimming. Never mind, it was my choice to submerge myself in the cooling creek water when most others wouldn’t have, and anyway, my nutrient rich organic diet, including some extra garlic, is dealing with the ear infection, and already the pain is subsiding as healing commences.
All of this sets the scene for a couple of blogs about building and maintaining garden soil fertility. This is such an extraordinarily broad and in-depth topic that all I can do in this blog is touch upon some of the ways I have added stable medium and longer term fertility to the soil. As an organic grower, I have not used any of the mainstream synthetic chemical fertilisers which can increase short term growth rates but at long term costs such as reducing the soil organic matter that holds on to nutrients, damaging soil biology that make nutrients available to plants, lowering plant nutritional value and increasing plant vulnerability to pests and diseases.
In retrospect, the seven years I have spent as a market gardener, I now consider myself as having been a student. My approach to garden fertility was basic – acquire and grow as much organic matter as time and energy allowed, mulch it onto the gardens around the plants if this was practical, or otherwise compost it, to be applied later. At the time, I favoured mulching because not only is mulch a slow release fertilizer (nitrogen from grass clippings, for example), but the mulch also suppresses weeds and works as a ‘sunscreen’ in the hotter months to help prevent gardens from drying out. I collected around 25 trailer loads of heavily manured sawdust from a local farmer’s cow wintering pads, some for composting, but most used either as a mulch on newly planted garlic cloves, and as fertile material to mound up around potatoes. Over the years I also purchased around 50 trailer loads of locally made compost, which I used as the main ingredient to make my own seed raising mix.
While mulching is a technique that I will always use, particularly in summer, I have become increasingly interested in composting in such a way as to build humus, that almost mythical substance made of decomposed organic matter transformed into a stable component of soil organic matter. Humus, being a home for beneficial microbes, holding up to ten times its volume in water, and holding and delivering nutrients to plant roots in symbiosis with microorganisms, seems well worth the effort to create.
To maintain fertility, I purchased and applied 3 tons of rock dust, around 4 tons of calcium carbonate (lime), seaweed & fish concentrate to the gardens. The calcium is such an important mineral to soil and plant heath that I intend to write a blog on it in the near future.