In God's fields rats are the problem. They crawled under the old maize stalks that Paul Kiongo Thuo carefully placed on his soil as mulch, as the missionary had shown him, and ate the seeds he had planted in neat rows the day after the rains came. Thuo killed seven of the rodents, but more have moved in. Perhaps it is best to let the seeds germinate first before laying down the mulch, his wife Grace suggests as they stand in the middle of their four-acre farm, where they also grow beans, bananas and cabbage. Thuo bobs his white beanie in agreement. Craig Sorley, a 6ft 3in American with a shaved head, Levis, a lumberjack shirt and muddy boots, listens and thinks for a moment. He has already sought advice on the rat problem from Christian colleagues in Zimbabwe who pioneered Farming God's Way, which uses biblical teachings to encourage a practice known as conservation agriculture. In reply, his colleagues had asked why raptors had not eaten the rats. But here, on the eastern edge of the Great Rift Valley in central Kenya, where small-scale farmers have traditionally struggled to grow enough food even to feed their families, virtually all the indigenous trees have been chopped down for firewood. The few exotic eucalyptus trees scattered around the farms are not suitable for nesting.
"You mess with one part of God's creation and you'll pay for it another," Sorley says, examining a handful of soil from Thuo's bean patch.
Sorley is a self-proclaimed environmental missionary. He represents the Baptist General Conference on the "conservative side of the evangelical movement" in the US. For many (perhaps most) of his church colleagues back home, the environment barely registers on the scale of challenges facing the world today. Climate change is still widely regarded as a myth, while creationism trumps evolution.
But for Sorley, 41, who discovered his calling after being diagnosed with a potentially fatal brain tumour two decades ago, global warming, environmental degradation and food and water shortages are some of the greatest threats to mankind today, particularly in the developing world. An easy-going, mild-mannered man who signs off his emails with "Blessings", Sorley becomes exasperated when trying to explain his church's reluctance to recognise the urgent need to protect God's creation.
"The deeply embedded view is that Christ is returning soon, so why should we care for the environment? Well, what if I had a child with leukaemia and I said to my wife, 'We don't need to give him food because he's going to die anyway'? Man, it's the same thing!"
In Kenya, where Sorley has chosen to test his pioneering mission work, it is clear that the natural resources are dying. A fast-growing population is putting huge pressure on both wildlife and the land. In April, a study revealed losses of hoofed animals such as giraffe, warthog and hartebeest of up to 95% in the famous Masai Mara reserve between 1979 and 2002, mainly due to human settlement around the park. The Mau Forest, the largest water catchment area in the country, whose rivers feed Lake Victoria and the Masai Mara, has lost a quarter of its trees since the early 1990s. In total, Kenya may once have had 8% of closed forest cover, scientists say; now it has less than 1.7 per cent. The resultant soil erosion is a major problem; the UN estimates that the dollar value of the soil lost each year is more than $2.5bn - more than three times the annual tourist income. Throw in increasingly erratic rainfall, apparently due to global climatic change, and decreasing agricultural yields and the prognosis is dire.
To Sorley, it is also an affront to God - especially in Kenya, where the clergy enjoys great respect and exercises significant moral influence. More than two-thirds of Kenyans are Christian, and church attendance is high - particularly in rural areas, where on Sundays families can be seen walking on the roadside in their finest clothes, Bibles in hand. Preachers offer a mostly conservative message of Christianity, with the gospel of salvation the main theme.
When not bumping along dirt roads in his 17-year-old red Land Cruiser, trying to persuade people to plant trees, harvest water and rejuvenate their soil in God's name, Sorley holds theological workshops. He often begins by asking whether anyone has ever heard a sermon about the environment. Faced with a sea of shaking heads, he then reels off the biblical verses that make his case, from Genesis 2:15: "The Lord God took the man and put him in the Garden in Eden to work it and care of it", through to Revelations 4:11: "You are worthy, our Lord and God, to receive glory and honour and power, for you created all things, and by your will they were created and have their being."
Even the biblically illiterate should be able to understand the message of caring for the environment, Sorley says.
"You've got Noah's Ark - talk about an endangered species programme. For animal stewardship you have the Good Shepherd. And everybody knows about the Garden of Eden."
Sorley spent much of his youth in east Africa. His father, a doctor, was a medical missionary and the family lived in Ethiopia until they were chased out during the Marxist revolution in the 70s. Later, they lived in Uganda during the rule of Milton Obote, where child soldiers with AK-47s occupied checkpoints and the Aids epidemic emerged with devastating effect. Sorley, who learned to appreciate nature while on long drives to boarding school near Nairobi, became aware of another impending crisis. "Even then it was visible that the forests were coming down and wildlife was on the retreat," he says.
After school, Sorley moved to Minnesota to attend a Christian college. He began getting recurrent headaches. The doctor ordered a CAT scan, which revealed a highly malignant brain tumour. He had immediate surgery, radiation treatment and chemotherapy. While waiting for the results of the treatment, he picked up a Bible. He says he opened it randomly to Psalm 103, which talks about praising the Lord who heals diseases, keeps one from the grave, and enables one to "stay young and strong like an eagle".
"It was the most spiritual moment of my life," Sorley says. "All my fears seemed to melt away, and my health reports have been good ever since."
At the same time, he says, "God laid a burden on my heart, to do with the environment."
While recuperating in Kenya for a few months, Sorley told a close friend that he wanted to pursue environmentalism, using the church to carry the message. His friend claimed that Christians didn't care about the environment. "It was an accusation, a challenge," says Sorley.
While studying environmental science at the University of Minnesota, Sorley sought evidence that would prove his friend wrong. He found none.
He became even more dismayed about the church's stance when looking at the mounting scientific evidence that climate change was caused by man, a conclusion he agreed with. He also accepted that the universe was billions of years old - "A testament to God's eternity" - rather than less than 10,000 years old, as creationist teaching suggests.
"Within the conservative church we really commit hypocrisy on this issue by the selective acceptance of science," Sorley says. "We reject the findings of climatologists and astronomers yet we would go to an oncologist - even an atheist, Buddhist or Hindu one - to get cancer treatment without batting an eyelid."
He saw it as his Christian duty to do something to help the victims of climate change. The Bible was the only weapon he needed.
Limuru, a 30-minute drive from the Kenyan capital Nairobi, was one of the favourite spots for the British settlers in the late 19th century. More than 2,100 metres above sea level, it has misty mornings, abundant rain; ideal conditions for growing tea. Among the emerald tea fields today sits Brackenhurst, a Baptist-owned conference centre that occupies 100 acres of land. So abundant are the trees and so rich the birdlife that visitors sometimes make reference to the Garden of Eden, which pleases Sorley.
He has his office and an indigenous tree nursery on the grounds, and also rents a small colonial-era house, where he lives with his wife, his two young sons, his dog and an augur buzzard, which he took in after it was found with a permanently damaged wing.
After moving to Brackenhurst in 2003, Sorley spent one year learning about Kenya's forests, and was deeply concerned by what he found. While there are more than 1,000 indigenous species in Kenya, their volume was dwindling due to deforestation caused by farmers seeking land to grow crops, or by people looking for firewood. Of the new trees being planted the vast majority were exotic species. Not only was this reducing the overall diversity of tree and plant species, but also the range of bird, mammal and insect species.
At Brackenhurst, a programme that started in 2000 to clear more than 12 acres of exotic trees planted for their timber and replace them with indigenous trees was already yielding promising results. Within a few years the number of bird species counted had tripled, Sorley says, while duikers, mongoose, monkeys and genet cats had all returned to the young forests.
In 2005, Sorley started up his own organisation, Care of Creation Kenya, to try to replicate that success elsewhere. He now grows 20,000 trees a year from 72 different indigenous species. The young trees are donated or sold for between 40p and £1.60 to local communities, schools and churches.
One chilly morning we drive to the All Saints Church in Limuru, a beautiful old stone building. The church purchased 50 young trees from Sorley two years ago, which now stand head high behind the graveyard. Weavers had built nests in several of the trees. At the Ngecha Primary School, a short drive but an economic light year away in a densely populated part of town, headmaster Joseph Mathenge escorts us around the school grounds where 600 of Sorley's trees had been planted since 2007. As kids in threadbare jerseys and battered shoes kick footballs made of rags, Mathenge explains how before, where there had been no shade for the 800 pupils to sit under; soon there would be a "forested park" outside the classroom block.
Kenya's most famous tree planter is the environmental activist Wangari Maathai. She attended one of Sorley's workshops just weeks before she won the Nobel Peace Prize in 2004, and was impressed by his approach. She had previously tried to persuade the church to champion the environmental cause, without success.
"People in Kenya are religious, but often in a superficial way. They look at God like he's a magician... rather than a God who wants us to use and protect the tools he has given us," she told me.
"Craig was talking about the environment from a biblical perspective, which I never heard anyone doing before. I thought at the time that if we could get that sort of language coming from the pulpit on Sundays then we would start to see all Christians looking to protect the planet."
Elizabeth Nyanga Mugo looks pleased. The soil beneath her toes is wet from the previous night's downpour, the biggest of the year. Earlier rains have been poor; farmers who planted seeds saw them rot due to the lack of follow-up rain. Now, in the early afternoon in Ndeiya, a 30-minute drive west of Limuru, the clouds are bruised and plump with precipitation again.
"We are very hard-working people," says Mugo, 48. "But only God can bring the rain."
Mugo owns 10 acres of land where she grows maize, beans, potatoes and bananas, some for her family, and some for sale. Her husband herds cattle.
Theirs has not always been a content existence. In Kenya the small-scale farmer occupies the lowest rung in society, "sometimes even below the lowest rung, in their minds", Sorley says. Though the farmers' toils feed most of their countrymen, they are regarded as peasants, people not to be emulated.
"After independence, to be seen as a modern African you had to be educated and get a job as a government clerk," says James Shikwati, director of the Inter Region Economic Network, a think-tank in Nairobi. "In my village if you farmed it was assumed that you failed at school."
Sorley says that when he meets farmers such as Mugo, they are often filled with despair at their decreasing yields and lowly place in the community. And while the ultimate aim of Sorley and his project manager, Francis Githaigah, a jovial 49-year-old ex industrial chemist, is to increase agricultural productivity through soil rejuvenation, first they try to repair the farmer's sense of self-worth through biblical teaching.
Githaigah, who navigates the dusty roads to Ndeiya on a Honda motorcycle, conducts discipleship classes for farmers, using Sorley's chosen biblical verses to build up esteem and provide theological reasons for environmental stewardship. Githaigah began planting trees around his mother's home near Mount Kenya in the 90s after seeing her struggle to find firewood, and describes farmers like Mugo as "my friends and disciples".
"Today, I feel strong in my heart about farming," says Mugo, who often has baboons and antelope wandering past her house. "We live here through the wonder of God - this land is our paradise."
Yet it is a paradise that is offering less to its custodians by the year. Sorley says that many farmers report yields of only a quarter of those achieved 25 years ago. Erratic rainfall is partly to blame but the main reason is that the soil is exhausted after decades of continuous farming using the same methods that extract nutrients from the earth but put nothing back.
As the pressure grows on farmers to produce more - Kenya is again facing a food crisis this year - local and multinational agricultural companies are trying to cash in. A better seed can improve yields, and companies have realised that the millions of small-scale farmers in Kenya represent a lucrative market. Shikwati, the economist, says that some firms have bought land alongside the main rural roads to showcase the effectiveness of their seeds.
But to Sorley seeds are not the answer. For starters, the seeds being hawked are mostly hybrids. The plants that grow will not produce seeds of the same quality, so farmers are locked into buying new seeds each year rather than saving their own. What's more, many of the seeds require fertiliser to be effective, Sorley says, which is too expensive for many poor farmers.
Sorley has set up his own demonstration plots to convince farmers like Mugo and Thuo that by caring for their land, in accordance with God's will, output can increase significantly. Conservation Agriculture, a method promoted by the UN's Food and Agricultural Organisation, calls for crop rotation and minimal soil disturbance, since tilling or ploughing can lead to a destruction of organic matter. The third key element is permanent soil covering - essentially putting down a layer of mulch that encourages micro-organisms to grow in the soil and which will eventually break down the mulch into a natural form of fertiliser.
On a quarter-acre plot next to Sorley's house he has been growing beans, maize, broccoli and potatoes using these techniques. In the maize patch the soil is barely visible under the rows of old maize stalks; for the other vegetables grass clippings and pine needles are the mulch. Last year his maize yield was more than double that of other local farmers, Sorley says. "Farming God's Way is based on science, and it makes sense for economic reasons. But small farmers are still reluctant to set aside land to experiment with - it's a risk for them - and they usually use the maize stalks that we would use for mulch as feed for their cows after the harvest. It is only when you add the biblical and moral mandate of good stewardship to the economic interest that there's a good chance of getting people to give it a try."
This year, for the first time, five farmers in Ndeiya have created their own test plots, including Thuo and Mugo. And while Thuo's rat problem has been a setback, the early signs elsewhere are positive. Mugo says that her neighbours have come around to examine the "crazy thing" she is doing to produce such an impressive crop. "One day soon we will be able to get electricity here," she says proudly. "Jeremiah chapter 17: He who trusts in the Lord is like a tree planted by the riverside."
This fusion of God and Green, especially coming from the conservative evangelical base, could be expected to sit uncomfortably with some leading environmentalists. George Monbiot, the activist and Guardian columnist, says that much of the opposition to climate-change science that characterised the George W Bush administration came from the conservative Christian base with ties to the big business agenda.
"There was also a refusal to accept that man could have an effect on the environment," he says. "It was 'God is in charge and omnipotent, so bugger off and leave us alone.'"
But Monbiot has no objection to evangelicals moving to the side of the greens, especially as they already have a large constituency that they can potentially influence in a positive way.
"We are facing a global crisis and we must use every tool at our disposal in preventing climate breakdown and a food and water crisis. I don't mind how the message reaches people or who is doing it," Monbiot says.
There are signs of a change in direction within the US church, driven in part by a realisation that the world's poor will suffer most from global warming, however it is caused. Last year a coalition of Southern Baptists, among the most conservative denominations in the US, issued a declaration on the environment and climate change, calling for a "unified moral voice".
"Our cautious response to these issues in the face of mounting evidence may be seen by the world as uncaring, reckless and ill-informed," the Southern Baptist Environment and Climate Initiative said. "We can do better. To abandon these issues to the secular world is to shirk from our responsibility to be salt and light. The time for timidity regarding God's creation is no more."
Still, it is just a small step forward. And in Kenya, where Sorley wants all seminaries and Bible colleges to teach mandatory courses in creation care, the top religious leaders have yet to show any strong intent to help tackle the steep environmental challenges facing the country.
Wangari Maathai says: "There are still few people of God going up on to our mountains to see how the natural forests are being cut, and how the rivers run red with silt."
Sorley acknowledges that a change in the broader church mentality will take some time yet. In the meantime he dreams of opening Care of Creation offices across East Africa, and more in Kenya, too, but says that church funding is far more difficult to obtain than if he were running a project for Aids orphans or street children. "This is still a new frontier for mission work."
