The soil is the foundation of agriculture, the world community is celebrating 2015 as “International Year of Soils” and the session of General Assembly is dedicated to increase awareness of healthy soils for food security and proper function of ecosystems. This increasing awareness of world community in managing healthy, productive soils is a positive sign for the future agriculture. World is facing serious challenges of population growth, more frequent occurrence of extreme weather conditions than in the past, therefore, healthy soils are essential to meet global food, feed, fuel, and fiber demands.
National Resource Conservation Service (USDA) provides four basic principles to improve soil health: 1. Keep the soil covered as much as possible, 2. Disturb the soil as minimum as possible, 3. Grow plants throughout the year to feed the soil, and 4. Use crop rotations and cover crops that diversify crops. These four principles will not only benefit soil by improving its health but also reduce input costs, protect against weather extremes and drought, and increase farm profitability. These four practices are beneficial for the following reasons: 1. helps prevent erosion by keeping soil covered, 2. minimum disturbance of soil retain soil structure, benefit soil organic matter, which provides crops and soil microbes conducive growing environment, 3. growing plants all along the year will harvest sunlight throughout the year, keep soil covered, enrich soil with organic matter and nutrients (if green manure and legume crops are included) and good growing environment for living portion of soil, 4. Crop rotations and diversified crop system help break weed cycle (reduced use of herbicides), pest cycles and soil borne diseases and promote diverse soil life by providing diversified food, 5. Farm livestock contribute by providing manure that increase soil microbes and add organic matter to soil.
Recent research has shown that corn – cover crops cropping system improves organic matter and yield as opposed to continuous corn-corn cropping system. Crop rotations conserve top soil; there have been long term study (100 years of research) comparing continuous corn and corn-oat-wheat-red clover cropping system. The long term research has provided strong evidence that the shorter rotations generally give more farm profit but longer rotations help in improving soil health and long term soil productivity. When soil under continuous mono cropping systems has decreased top soil by erosion consequently reduced water holding capacity is the major yield limiting factor, and addition of chemical fertilizers has limited utility in bringing back soil health.
A long term study (100 years) on cropping systems and nutrition management exhibited that addition of farm yard manure increased organic matter compared to N-P-K fertilizer and cropping system with legume was better in improving soil health than continuous growing of maize. Scientific studies show compelling evidence of the value of maintain soil quality in various crops and environments, yields may be maintained for a while without proper caring for the soil health, but if soil organic matter is not properly maintained, soon crop yields drops as well.
Maintaining soil organic matter and top soil increase water-use efficiency because soil organic matter improves water holding capacity. Under rains, good amount is held into the soil rather than loss by runoff and causing erosion problem. The absorbed water can be used for growing crops. Benefits of soil organic matter include improved soil tilth, meaning roots more easily explore soil, increases living portion of soil (soil microorganisms) thus improving the soil quality. Building and maintaining soil organic matter will not only increase the ability of soil to grow crops but also make a big difference in soil health thus sustaining the soil productivity for future generations. Keep the soil covered by growing cover crops by incorporating in to a crop rotation also contributes the soil fertility and to further build soil organic matter and soil microbes.
The cover crops reduce erosion, improve soil tilth, increase water-infiltration, break weed and disease cycles, capture nitrogen not used in the previous crop, provide nitrogen for the next crop if legumes are used for the cover crop and provide grazing for livestock. Addition of farm yard manure provide long term health benefits to soil and crop productivity even if short term monetary benefits do not favor using manure.
Improving soil health might be an effective way to hedge against climate change and help keep growing crops profitably for future generations under predicted weather extremes. Healthy soils could play a crucial role in food safety, food security, adaption strategy to extreme weather events, poverty reduction and sustainable development of world.
interesting reading: Restoring soils could remove up to ‘5.5bn tonnes’ of greenhouse gases every year