By Keith Jordan
In an ‘average’ year, the Cambridge area generally has annual rainfall levels between around 510 – 610mm (20-24”) – similar to parts of the Middle East and Cyprus, Corsica and Sicily. This year rainfall levels are even lower (so far) making gardening much more of a challenge. Welcome rain between June and August perked up many summer/ autumn crops – courgettes, runner beans, potatoes, chard, autumn raspberries, apples and pears. Healthy crops and good yields are dependent on good soil moisture levels, especially during the months of higher temperatures and sunlight levels.
Planning for potential drought in 2012, you can start now by increasing the organic matter of your soil (this traps moisture in the soil and increases fertility). Make as much compost as you can (including collecting leaves this month!) and if necessary bring in manure (from a reliable herbicide-free source). Once rotted, this can be spread on the soil or traditionalists can dig it in. Sow green manure crops on any bare soil now.
Once grown, but before flowering, plants are dug in, where they decompose in situ, boosting organic matter levels and thereby water retention properties. Make ‘trench’ compost heaps where you plan to grow water-hungry plants like runner beans, courgettes and squashes next summer – dig a trench and gradually fill with compostable materials (but not weeds that have seeds). When full, cover with soil and allow to rot down over the next 8 months. Use mulches around permanent crops like fruit trees, especially biodegradable materials like cardboard, to reduce weed growth whilst keeping water in the soil where you want it.