A lively debate exists among gardeners on how much the ground should be disturbed for successful gardening. Tilling the soil before planting may lay claim to being the traditional method, but no-till advocates have been gaining ground. Looking at each practice and the advantages and disadvantages of both is the only way gardeners can decide their own course of action.
Whether it's with a garden fork or a rototiller, the basic idea is the same; tilling the ground involves digging down to the depth roots will go (the root zone), and turning it over. Advocates claim this loosens the soil properly to aerate it and allow for comfortable plant growth. Do make sure that the ground is not too wet, or turning the soil will make clods of mud with little other benefit.
Is "no-till" really no-till? Well, not exactly. For a plot of land that hasn't been gardened before, the ground is likely too hard to poke a few seeds in holes and expect happy plants to come up. But once the ground has been properly loosened once, proponents stress that the soil only needs regular additions of all important biomass, like compost and leaves, to remain optimal for garden growth. Worms and plant roots do a better job of keeping the ground aerated and light, say no-till devotees.
Tilling eradicates growing weeds, mixes the soil for even consistency, and ensures that it is loose enough for plant growth all at once. Organic matter mixed into tilled soil decomposes more quickly than that left on the surface, making it bio-available to the plants that much faster.
Ironically, tilling to remove surface weeds could exacerbate the weed problem later, as the weed seeds in the churned-up dirt are now exposed to the sun where they can sprout. Tilling, especially with machines, can create compacted soil (hard pan) just below the reach of the blades. Breaking up and mixing the soil disrupts the delicate habitat for earthworms and other beneficial organisms. Erosion and "dust bowl" conditions can result from small soil particles not protected at the surface.
No-Till Gardening Advantages
No-till proponents point out that weed problems are almost a thing of the past, as long as the additions of biomass don't contain viable seed. The spongy top layer of untilled soil holds water right where the roots need it most, and the undisturbed beneficial soil organisms flourish. There's a certain amount of labor saved by not having to turn the soil before planting, too.
Insect and fungal pests may have be encouraged if spent crops aren't removed and composted hot before returning to the plot. Sow bugs and slugs have lots of places to hide with non-tilled soil. The lighter-than-ground-color mulch can slow warming of the soil in the spring. Direct-seeding some plants can be problematic as the sprouts have to negotiate their way to the sun through excess decaying plant matter. All that composting biomass on top of the soil makes the garden look messy to the unenlightened.
Perhaps both methods have their proper place in gardening. Direct-seeding often needs the smooth, clean, small-particled soil of a tilled garden. But transplants might appreciate the natural mulch around them from a non-tilled growth medium.