I don't like using "chemicals" on the farm. I'm sometimes asked if we farm organically (as our neighbours do, with their cute little Dorper lambs gambolling around at the moment), and I usually reply "nearly". Organic except for Roundup. Roundup is brand name for glyphosate, a weedkiller that is supposed to be one of the least harmful to the environment. It doesn't hang around in the soil for long, and is very effective. We used it to keep the soil around our trees free of weeds, so that the little plants could grow without competition from grass and stuff. It makes a big difference to their rate of growth. Now they're big enough to look after themselves, our usage has gone down markedly. Last year, I hardly used any at all.

One reason for that reprehensible failure to enrich the purveyors of agrichemicals was the discovery that glyphosate seemed to have a bad effect on certain mycorrhizae - the "fungus roots" formed by fungi living in symbiotic associations with plants. I have some Pinus radiata (Monterey pine) infected with Lactarius deliciosus (Saffron Milk Cap) as part of a trial with Crop & Food Research , the scientific outfit who got truffle growing started in New Zealand. I used Roundup round them when first planted, and I haven't yet produced any mushrooms, whereas those left to their own devices in other plantations have all produced. I hope mine recover! When that bit of bad news hit home I took a strategic decision not to use Roundup in the truffière on the grounds that it might be have some similar sort of effect. Last year's weed control was done by hand - or to be more exact by weed eater. But then a neighbour who has trees the same age as mine started producing truffles - and he'd used Roundup. I reviewed my strategy. This year, one spray in spring before doing the soil work will suffice, then the weedeater will go back to work.

Yesterday was a magnificent day — cloudless, still, and after a light ground frost dried off, warm enough to discard sweaters and sunny enough to require sun cream. A perfect opportunity to do some spraying. I didn't have any mechanical problems, the wind didn't start blowing the minute I reached the truffière (as it usually does), and all was right with the world. But I felt guilty. Having eschewed the stuff that screwed up my milk caps, here I was applying liberal quantities (actually, given the way I felt about it, it was probably neo-con quantities) to the soil. My fingers are firmly crossed.

Next job was to feed the citrus trees that grow along the north side of the house. Several lemons, limes, a cumquat, tangelo, mandarin and grapefruit make a rather snaggle-toothed but fruit-laden bed, and over winter they've been developing yellow leaves.

Tangelos, yesterday. Very tasty indeed.

In our high lime soil, this means not enough magnesium, so the first step was to apply liberal quantities of Epsom salts (magnesium sulfate). Then a general citrus fertiliser. I bought a bag of Yates finest, and set to applying the stuff. Then I read the label. "Use of this product may result in cadmium and mercury levels in fruit above permissible levels." What? I read it again. Apparently this fertiliser, specifically designed for citrus and fruit trees, which - and please correct me if I'm wrong - people normally grow because they want to eat the fruit, will eventually poison the fruit to the extent that we shouldn't be eating it! Can this be legal? Being realistic about this, I suspect that they have to put that statement on their product even though the risk of it actually happening is small, but even so, had I read the small print on the label on the shop, I would have bought another product. I shall cerrtainly use no more.

My father, bless his large cotton socks, suggested an organic alternative that involves citrus skins and copious quantities of human urine. I would welcome a more savoury alternative.

Next task: driving the tractor and cultivator round the truffière…