화석연료 화학비료 대 액비

관행적인 화석연료로 만든 화학비료는 토양의 생명과 야생 동물을 파괴하고, 농민들은 마약처럼 그에 중독되었다. Rebecca 씨는 농장에서 NPK 대 집에서 만든 액비로 실험을 해보았다. 

우리의 땅을 푸르게 만들지만 그리 유쾌하진 않다

정원이 있으면 Miracle-gro®, Phostrogen®, Baby bio®, Growmore®나 기타 화학비료의 이름의 이름 하나 정도는 알고 있을 것이다. 농장에서는 'super triple 인산비료', Nitram®, '20:10:10', 그냥 '질소'나 –좀 완곡하게– 화학비료라고 불린다. 우리 농장에서는 간단히 그 화합물의 일반적 화학성분의 약어인 NPK –질소, 인, 칼륨 라고 부른다.

합성 화학비료는 근본적으로 인구성장의 한계를 극복하고자 개발되었고, 세계 인구의 거의 절반이 현재 그걸 사용한 직접적 결과로 먹고 산다고 추정된다. 그러나 이런 '세계를 먹여살리기' 위한 묘책은 확실히 비용을 치르고 있다; 광대한 바다에 죽음의 구역부터 겉흙에 중금속의 축적하고 대기로 온실가스를 배출하는 것까지.

난 합성 화학비료의 세계적 장점이나 단점을 토론하려는 것이 아니지만, 그게 우리 농장에 오면 NPK에는 명백한 여러 단점이 있고 진정한 의미의 지속가능성이 결여 되어 있기에 난 몇몇 근거를 대며 그냥 바닥에 내던져버릴 것이다. 인(Phosphorus)과 칼륨(Potassium)은 모두 고갈되고 있는 광석에서 채굴하고 질소(Nitrogen)는 막대한 양의 천연가스나 석탄을 사용하여 공기에서 추출한다.

오른쪽 농지의 녹청색은 NPK로만 가능하다

우리 농장에서의 목표는 경제적, 생태적, 사회적으로 회복력을 갖춘 사업을 창출하는 것이라서, 농장에서 비옥도의 기초로 고갈되고 있는 해외의 자원인 화석연료에 의존한다는 생각은 완전히 미친 소리다. 그러나 NPK 사용을 그만두는 것은 생각만큼 간단하지 않다. 수십 년 동안 농지에 그걸 즐겁게 뿌린 내 아버지조차 농민이 화학비료를 사용하는 건 마약중독자가 마약을 하는 것과 같다고 표현한다. 

마약에 대한 비유는 새로운 것이 아니지만, 난 많은 사람들이 그것이 어느 정도 수준까지 빠지게 되는지 잘 모른다고 생각한다. 마약중독처럼 첫 경험이 최선이며 그때부터 확 빠진다. 

첫 경험이 그렇게 좋은 까닭 중의 하나는 실제로 아직까지 제대로 기능하는 살아 있는 흙의 비옥도에 '식물의 영양분'을 순수하게 추가해 주었기 때문이다. 난 종종 내 아버지와 삼촌이 유기농 농지에 NPK를 처음으로 주었을 때 보았을 놀라운 성장속도가 궁금하다. 

당연히 토양의 필수적인 식물 영양분과 미네랄은 토양 생물들에 의해 만들어진다. "한번 미네랄이 생명이 되면, 그건 모든 생물이 쓸 수 있다"는 속담처럼, 토양 미생물에 의해 미네랄이 한번 만들어지면 식물이 이용할 수 있는 영양분이나 다른 미생물을 뒷받침할 수 있게 된다. 

건강한 토양에서 미생물의 순수한 양과 종류는 깜짝 놀랄 정도다. 유기농의 건강한 토양에서는 숟가락 하나 분량의 흙에 약 10억 마리의 미생물이 살고 있다. 당신이 Elaine Ingham 박사나 Patricia Richardson 박사와 같은 과학자처럼 비슷한 일을 한다면 아마 전자현미경으로 이 놀라운 지하세계의 전모를 볼 것이다.

지하세계를 엿보기

It's a world full of fungal forests and peculiar plants, of bizarre little grazing herbivores that are prey to fang-toothed hunters that in turn are devoured by positively petrifying looking apex predators whose dead bodies are scattered by innumerable little scavengers. They are all their under our feet, unseen.

What's not so commonly known is when you first sprinkle on the NPK these microbes die off in their trillions with each tiny body releasing a small package of nutrients to the plant roots around them. To the naked eye we just see an impressive surge in plant growth but on the microscopic scale it is the apocalypse!.

The pitiful sight of the dead and dyingIf, like us, you're one of those farmers or gardeners without your own electron microscope, there is one soil dweller we can observe that can tell us all we need to know about the life in the soil and the effects of chemical fertilizers – the earthworm. We all know that a soil rich in earthworms is healthy and fertile so you can imagine how distressing it was to find dead and dying worms scattered across one of our fields during the first rains after the NPK had gone down.

Like an addictive narcotic, once you start using synthetic fertilizers, it is a one way ride. Each application onto to fields burns off more and more soil biology which in turn severely reduces the amount of available minerals and nutrients from the soil to the plants. Each year you have to add a little more just to stand still and eventually it's a case of add the NPK or go out of business.

Holistic Rancher Greg Judy sums it up by saying, "When you put chemical fertilizer down on your farm you're killing your farms future, and the fertilizer companies are laughing all the way to the bank because you've now got sterile soil, and they know you've got to comeback to them to buy more of their fertilizer."

That's the trap my father and uncle are seemingly in, the only way they view they are going to get any growth out of our fields is by mainlining a direct hit of chemicals straight into the plants roots because they no longer can rely on the now impaired soil biology to help grow healthy plants.

It is possible to wean your farm off chemical fertilizer but it's not easy – it's called 'organic conversion'. As any farmer who has made the move to organic can tell you, going cold turkey from synthetic NPK can be a painful business. Curiously it is not just the land that becomes addicted, the whole way of working the land changes and, in effect, the farmer is just as hooked as his soil.

Intriguingly over the last couple of years since we've started applying pressure for my father and uncle to stop using the stuff, that junkie farmer mentality has unwittingly risen to the surface.

The tale starts four years ago, Tim (my other half) and I sat down with my father and discussed the damaging nature of synthetic NPK. He completely agreed with us and promised not to spread it on the fields on the west side of the farm as a small trial.

The depressing shaker sound of the fertilizer spinnerThe following week I heard the unmistakable rumba-shaker noise of the fertilizer spinner... it was in the next-door field to me. Dad had purposely driven the long way round the farm to avoid driving past Tim and myself so he could 'fertilize' the fields he promised not to touch.

That was just the start or this behaviour; since then they've taken to hiding their NPK 'stash' behind the backs of barns in the hope we won't find it. Each year they may have got away with it if the deliveries hadn't been the same size as a grey whale.

They promise not to buy as much only to either buy the same amount if not more each year. Even the language they use sounds like an addict, "Oh I've only used a little bit", "I used to use a lot more then I do now – I've cut right back", "You're right we should give it up... but we've bought it all for this year now so we can't waste it".

The point being my father fully admits NPK is bad for wildlife and knows it damages the soils and is dangerous in waterways and doesn't like using the stuff yet, like a person with a habit, he'll go into complete denial when actually out scattering it on the fields.

The not so secret stashAs a result we realised pretty early on that if we were going to make any headway we needed to find an equivalent to soil methadone to try and wean the Old Boys off their magic white granules.

Our answer came in the form of cold brewed aerobic compost tea. Compost tea (or more correctly, we think, compost beer) has grown and grown in popularity over the past few years, particularly with gardeners but is now making headway into the world of farming. You can make it at home for next to no cost and, if brewed correctly, it's packed full of beneficial micro-organisms who then provide the  'fertilizer effect' by making biologically available those nutrients already present in the soil.

We started using it three years ago and risked a head to head challenge to prove to my father and uncle this bizarre alternative had some merit.

homemade compost brew bubbling awayMy father doused half a field in NPK and we sprayed the other half in compost tea. When it came to hay harvest time we all walked the two sides of the field to compare the results. Stupidly I never took any photos that day but although the sward wasn't as heavy with the compost tea it still held its own to the fertilized side. Particularly seeing we made the tea for pennies compared to the hundreds of pounds spent on fertilizing the other half. As a result of that trial, the following year we were given the go ahead to spray an additional field and this year a couple more.

In our case, the biggest benefit from using compost tea was to stop the NPK going down which is essential if our soil life is to start building again. Rule one for regenerative agriculture should be the same as in medicine – do no harm! The added bonus of compost tea is that by adding trillions of beneficial microbes it should also be helping to jump-start the biological cycle within the soil.

Tim's made from scrap and less than £50.00 compost tea sprayer

There are some farmers we know of who swear by compost tea and apply it in quantity several times a year but, for us, we see it as a temporary measure. By changing our land management and grazing practices, we hope to rebuild a truly healthy, self-sustaining cycle of life in our soils powered solely by the sun. Compost tea application will definitely have a role to play in getting things started but hopefully we won't have to apply it for too many more years. To use a thoroughly inappropriate analogy, compost tea is our starter motor and we will only be using it until the main engine kicks in.

Useful links

PDF from Elaine Ingham on compost tea

Video clips of Paul Taylor on making compost

Teaming With Microbes - the organic gardener's guide to soil food webs reviewed by Patrick Whitefield.