Soil is one of the most important natural resources, is the medium in which our food, clothing and shelter are produced. It is created by a slow and constant physical and chemical breakdown of rock and the action and turnover of living organisms. It takes approximately 500 years to replace 1 inch of soil by these process, making it critical to keep the soil fertile and productive as well as to prevent erosion. Plants are not independent organisms but are highly dependent on many critters in the soil- fungi, bacteria, nematodes, micro-arthropods, protozoan, insects, worms etc.
The foundation of organic farming lies in the health of the soil. A fertile soil provides essential nutrients to a growing crop plant and helps support a diverse and active biotic community. If the soil is not healthy, the plant will not be either. So, in an organic system, feeding the soil is a primary way to help nourish plants, fight disease and pests and to feed the soil, organic matter should be added every season. Organic matter includes:-
Animal manures: Livestock manure is being used to fertilize soils of both organic and sustainable farms. Animal manures provide essential nutrients required to grow healthy plants. In addition, animal manure adds organic matter to soil, improving microbial activity, water drainage and overall soil structure. However, not all animal manure is suitable for fertilizer: For example, cat and dog manure are not usable. The best animal manure fertilizers come from livestock, fish, worms and even bats.
Cover Crops: Cover crops are annual, biennial or perennial herbaceous plant and these crops provides cover and helps in loosening compacted soil through the root growth and improve water infiltration. Cover crop prevents soil erosion caused by both water and wind, suppress weeds, and reduce insect pests and diseases. In addition, a legume used as a cover crop provides nitrogen to the soil. Common cover crops are cow peas, forage sorghums, rye, buckwheat, sweet clover and millet.
Green manures: Green manuring is the practice of ploughing or turning into the soil the green plant tissue for improving the physical condition as well as fertility status of the soil. During decomposition process by the organisms in the soil, organic matter and nutrients become available to the crop plants. Also green manure suppresses weeds and soil borne diseases, increases soil’s biodiversity by stimulating the growth of beneficial microbes and other soil organisms. Eg:- Sun hemp, dhaincha, cluster bean, Ipomea, karanj (Pongamia glabra), Gliricidia sepium, Sesbania speciosa, Jatropa gossipifolia, Sesbania grandiflora, Leucaenea leucocephala and several species of Acacia and Prosopis.
Crop rotations: Crop rotation is the growing of different crops in a regular order on a same land for a fix period keeping in view of the fertility status of soil. Crop rotation also reduces erosion, insect and diseases risk and diversified farm income. In the rotation, leguminous crop-non leguminous crop, more exhaustive crops-less exhaustive crops e.g. potato, sugarcane, maize- oilseeds, pulses, erosion promoting crops (millets)-erosion resisting crop (legumes) should be included.
So, the operative activity should not be feeding plants but rather encourage a healthy soil ecosystem in which plants will naturally thrive and play a part in maintaining these cycles.
Dr. T Esther Longkumer
ACTO-Soil Science
KVK Phek, ICAR-NRC on Mithun
