Yesterday evening I read ‘Growing Green’, by Jenny Hall and Iain Tollhurst, which had been recommended to me by a friend, Nick Vowles. There was a lot in the book that I already knew, but, as always, there is always something new to learn. The book is about Stock Free Organic farming, and much of the book is devoted to listing the standards that you need to adhere to to be registered. The book deals with farming at all scales, so quite a bit of it, the bits that dealt with machinery, were of little relevance, but there was enough new information to have made the purchase worthwhile. The main topic that caught my attention was the recommended amount of compost to use., which was one wheelbarrow load per 10 sq meters, for most crops, dropping to 5 sq meters for Nitrogen fixers, and some other crops.
A quick bit of mental arithmetic showed that I have been applying four times as much compost as they recommend. I wouldn’t normally worry about having too much compost, but they did say that an excess of Nitrates can lead to pest problems. So I’m having a rethink. Whilst my polyculture experiments are aiming at providing all of the fertility for the vegetable growing area, and may lead to a reduction in compost, I currently get through at least a bale of straw a week as bedding for the ducks and chickens. Buying that in creates a surplus of organic matter that I have been gleefully turning into compost, fully aware that I am importing fertility from somewhere else. So either I am going to keep on creating a surplus of compost, or I will need to produce more bedding material for my poultry, or I am going to have to find/develop a system that uses less straw.
Another interesting point raised by the book was that leaving bare soil over winter is one of the principle causes of soil erosion. Now I aim to keep all of the empty beds covered with compost, but the beds that have winter crops in still have a lot of bare soil. That’s something that I’m going to have to look at. Another useful topic covered by the book was which crops do/do not grow well with a groundcover. Sadly many of the plants that I grow at this time of the year are unable to compete with a groundcover, so I’m going to have to try mulch. Some of the plants will cope though, so I’d like to give that a try, but it does introduce another cost, or task. Buying, or growing, the seed for the groundcover layer. Plenty to think about.
The book gives some interesting crop rotations, including green manure details, and for anybody looking to establish a Market garden, it would certainly be useful.
I was also reminded that small branch wood, less than 7cm/3 inches have an almost ideal carbon/nitrogen ratio for use as a longer term soil improver. The lignin in the wood will take much longer to break down, but will not lock up nitrogen in the same way that older wood can. Again, this suggests ways that can help build fertility, such as sections of fast growing trees, or bamboo, perhaps as shelter for chickens, where small wood is shredded, and added to vegetable beds, possibly after use as bedding. Again, this is taking fertility from one area to another, but if the chickens are being fed from the vegetable patch, the system becomes much tighter.
On the downside, quite a lot of the techniques discussed come from Eliot Coleman’s book, New Organic Grower, which I already have, and may be a better buy.
The question remains, am I using too much compost? Perhaps I am. It may be that instead of scraping around to find enough ‘green’ material to make compost, that I use the old straw as mulch, or as a soil amendment. Removing excess Nitrogen, but still gaining from improved soil structure.
Plenty to think about during the cold dark winter.
Wishing you well