Research and Development
Weeds: Friend, not Enemy, of a Farmer
In a country like India, a variety of weeds rapidly cover bare ground with the first showers of the rainy season. When torrential downpours follow as the monsoon progresses, weeds buffer the hammering force of raindrops, while their roots bind soil against erosion. Such soil erosion could otherwise be severe in our tropical conditions, particularly on sloping terrain. Bhaskar Save, the ‘Gandhi of Natural Farming’, an educator, entrepreneur, farmer and activist, observes – it is our foolish ignorance that we fail to understand how great a blessing the weeds are!
The roots of weeds also improve aeration in the passages they make in soil. Moisture absorption and retention are higher. By shading the ground, weeds moderate the temperature of earth, reducing evaporation and maintaining suitable conditions for soil organisms. And when weeds die, earthworms, ants and decomposer-bacteria that feed on their dead leaves and roots, return their mineral nutrients to soil to help next generation of plants, and long life-span trees.
Weeds may additionally perform a variety of specialised functions. As soil conditions change, there is a natural progression of different kinds of weeds that inhabit the earth. Some are excellent pioneers that steadily work to improve soil where little else yet grows. Some are leguminous, and provide nitrogen. Yet others may function as reproduction inhibitors of little insects, thereby checking the plant damage that some of these creatures might cause.
When Weed Control is Needed and How
While weeds, in general, are friends of a farmer, in certain unnatural conditions, some species may become stubbornly rampant. Such weeds may then be a nuisance if they rapidly overgrow the crops planted by the farmer, blocking off sunlight. However, here too, the weeds help check and heal a more fundamental problem – that of soil erosion or impoverishment. They persistently signal to the farmer that s/he is planting a wrong crop in the given circumstances, or growing it in a wrong way, hurting the earth and her creatures.
The only sensible and lasting ‘root-cure’ to situations of weed rampancy among field crops is to adopt mixed planting and crop rotation, while discontinuing chemicals and deep tillage. Since the problematic weeds will only phase out gradually as soil regains its health, they may still tend to over-shade the food crops in the interim period of recovery. The way to manage this is to periodically cut weeds (before they flower), and mulch them at least 3-4 inches thick on soil under the crops. Without any sunlight falling on weed seeds buried in soil, their fresh germination is effectively checked.
There may, thus, be some competition between crops and weeds for sunlight, though not for soil nutrients. If crops emerge taller, says Bhaskar Save, their shade will suppress the weeds, which will then be unable to cause any problem. This happens naturally in healthy, living, non-acidic soils. Our ancestors have been farming for many generations. But because their soil was healthy, they never faced any serious problem from weeds, even as recently as a few decades ago.
There is thus a thumb-rule for seed spacing while planting your crops. If your soil is poor/weak, increase the quantum of seeds you plant. In other words, plant closer. By this stratagem, crops cast shade on the ground more rapidly, retarding weeds. If, however, your soil is fairly healthy, plant fewer seeds, that is, keep a larger gap between them.
When farmers shift back to organic farming, their soil steadily improves in health each year. Correspondingly, crop growth gets better, while weed growth declines. In just 2-3 years, there should be no need for any weeding at all. Until then, the farmer is better advised to cut and mulch the weeds.
Cutting of weed growth above land surface – without disturbing the roots – and laying it on the earth as ‘mulch,’ benefit soil in numerous ways. With mulching, there is less erosion of soil by wind or rain, less compaction, less evaporation, and less need for irrigation. Soil aeration is higher. So is moisture absorption, and insulation from heat and cold. The mulch also supplies food for earthworms and micro organisms to provide nutrient-rich compost for crops. Moreover, since roots of weeds are left in the earth, these continue to bind soil, and aid its organic life in a similar manner as mulch on the surface. For when the dead roots get weathered, they too serve as food for soil-dwelling creatures.
Correct Mulching Method for Weed Control
Mulching is effective in checking the rapid re-emergence of the cut weeds, only if mulch layer is thick enough to block off sunlight. For example, weeds cut from a plot of 100 sq ft will never provide a thick enough layer to fully cover the entire 100 sq ft. It may be adequate for 25 sq ft, or perhaps just 10 sq ft, depending on density of weed growth. If sunlight penetrates through a layer of mulch that is too thin (less than 3 inches), the weeds may grow back vigorously again.
Thus, if 10 sq ft is the area that can be adequately mulched, at least 3-4 inches thick, with weeds cut from 100 sq ft, that is what the farmer should stick to, unless additional biomass can be obtained from an external source. The fresh weed growth from the balance unmulched land would again need to be cut and mulched in the selected area. In this manner, the mulch method of shading out weeds can be successful in 4-5 stages. The decomposition of weeds may take several months, but the compost formed will be very helpful to the crop. What was viewed as an enemy, will now serve as friend!
It is also important that cutting and mulching operation should be done before weeds have flowered and become pollinated. If the farmer is too late, and the mulch contains pollinated weed seeds, a new generation of same weeds will re-emerge strongly in mulched areas.
Weed Control through Over-shading Plants
The Dabhro weed is considered a menace by most farmers. To control it, one need to plant crops that thickly shade the ground, says Bhaskar Save. No matter how often you remove it, the dabhro comes up again from its deep reaching roots. You cannot destroy it this way. Rather, you should plant an over-shading crop like banana at 4 ft by 4 ft, or 5 ft by 5 ft. When these have grown a little, provide them a good quantity of dung manure. The leaves that emerge will span out such that canopies of adjacent plants will touch, thickly shading the ground and thereby suppressing the dabhdo, and gradually destroying it.
Above the ground cover of weeds that constitute the lowest storey of vegetation in orchard area (where any sunlight penetrates to the ground), there are numerous shrubs like the ‘kadipatta’ (or curry leaf, Murraya koenigii) and the homely croton that line the pathways through the orchard. The latter plant, of various spotted and striped varieties, is relatively shallow rooted. It serves as a ‘water meter’, indicating by drooping of its leaves that the moisture level of soil is falling!
The shrubs of curry leaf contribute to moderating the population of several species of crop-feeding insects, while also providing an important edible herb widely used in Indian cooking. From this minor crop alone, Bhaskar Save earns an income of at least `2,500 each month, at zero cost. (Even the harvesting and bundling is done by the purchaser.)
Here and there, one might see climbers like the pepper vine or betel leaf in a spiral garland around a supari (arecanut) palm, or perhaps a passion fruit vine arching across a clearing. These provide additional bonus yield.
“In nature, every humble creature and plant plays its role in the functioning of the eco-system. Each is an inseparable part of the food chain. The excrement of one species is nutrition for another. In death too, every organism, withered leaf, or dry blade of grass leaves behind its contribution of fertility for bringing forth new life.” Consequently, pleads Bhaskar Save -- if we truly seek to regain ecological harmony, the very first principle we must learn to follow is, ‘Live and let live’.