Combining fruit tree or timber growing with annual cropping in between boosts growers' productivity without the need for more inputs, through farming "in three dimensions", a pioneer in so-called agroforestry systems told a conference on crop diversification last week.
Abacus Agriculture director, vice-chair of the European Agroforestry Federation and "simple farmer from Cambridgeshire" Stephen Briggs said field growers "rarely think more than 2ft above the ground or 1ft below it" but mixed growing systems "give you more space, if not more land".
Rows of trees tend to root deeper underneath the main arable or vegetable crop than they would otherwise, he explained, leading to "a completely different root structure". He added: "This brings up nutrients from deep down that are then dispersed on the surface via fallen leaves."
The system extends growing not just spatially but temporally because annual crops tend not to make full use of sunlight in the latter half of the year, he explained. "One hectare of agroforestry gives you 0.8ha of agriculture and 0.6ha of forestry - a land efficiency ratio of 1.4 or 40 per cent more productivity".
The addition of trees also offers environmental benefits, said Briggs. "They intercept rainfall, slow run-off and soil erosion, regulate wind speed and even hinder distribution of pests and diseases." Such systems have also been found to reduce nitrogen leaching from "leaky" fields by up to 50 per cent while also boasting greater diversity of wildlife, he added.
But he conceded: "Land tenure is an issue. Why invest if you don't own the land, given the long-term nature of the profitability?" This had a bearing on his own decision to plant apple trees on half of his 100ha of rented land, he said. "Apples are eligible for the Single Farm Payment and we have just a 15-year tenancy, while timber takes 30 years to harvest."
Having selected a range of later varieties so as not to overlap with harvesting of other crops of cereals, leeks, broccoli and red beet, he planted 4,500 trees in 2009, equating to a 10th of the density of a conventional orchard, in 3m wildlife strips, each 27m apart to give access to a combine harvester.
The trees are now yielding around 80 tonnes of fruit for juicing and fresh sale. "I also think it enhances the landscape," said Briggs.
He added that he now considers conventional orchards "a terrible waste of space because there's nothing growing between the rows".
Lagging behind Mixing field and tree crops
The UK lags behind other parts of the world in mixing field and tree crops, said Abacus Agriculture director Stephen Briggs.
"The biggest increase is in sub-Saharan Africa, while in the Chinese province of Henan alone there are 3.2 million hectares of agroforestry," he pointed out. "The total UK cropping area is 4.7 million hectares."
From January, growers in Scotland, Wales and Northern Ireland, but not England, will be eligible for EU agroforestry funds under the rural development "pillar" of the revised Common Agricultural Policy. Briggs was one of 23 industry signataries on a letter to Defra in March urging it to adopt the measures also, but without success.