After the United Nations Climate Change Conference 2009 in Copenhagen, environmental protection and low-carbon have been brought into spotlight. Due to the climate change, people have focused on how to do the green thing. We should live and produce in a low-carbon style. How to do this? You should pay much more attention to materials that were used in the production.
Cotton is natural, renewable and recyclable. But do you know that when cotton is planting, the soil is ruined. Over the last half-century, U.S. cotton growers and researchers have collaborated to improve the conservation of the natural resources used in cotton production -soil and water- while protectin air quality and improving energy efficiency throughout cotton’s life cycle.
A variety of farming techniques, such as conservation tillage – mixing and disturbing the soil as little as possible – and planting winter, or cover crops, have been modernized and improved upon to conserve soil by preventing erosion and by actually helping to encourage soil creation. According to the U.S. Department of Agriculture (USDA), total soil loss on cultivated cropland across the country decreased by nearly 40 percent from 1982 to 2003. This trend is indicative of modern agricultural technologies that enabled the preservation of more soil and the concurrent development of higher-quality soil.
Cotton Growing Systems and Techniques Conserve Soil Resources
Over the last 10 years, cotton has made great strides in reducing the use of tilling and in adopting the practice of growing winter or cover crops. Scientii c research shows that these improved conservation tillage practices dramatically reduce soil erosion, and actually bring these activities into balance with soil creation.
Modern production practices allow cotton growers to achieve high levels of soil conservation and input efi ciencies that both increase yield and reduce production cost. The environmental and economic benei ts, coupled with mandatory regulations and requirements for compliance, are strong incentives for producers to take every practical measure possible to protect the soil.
Cotton is highly tolerant of soil and water salinity (salt content) and can be grown with water and soil resources that would otherwise be unsuitable for other food, feed, and fiber crops. Cotton’s high level of tolerance of salinity lets producers make use of drainage or reclaimed water that otherwise would require environmentally-challenging waste disposal, another achievement of modern farming technology in practice.
Conservation Practices to Control Soil Erosion
Modern agriculture now uses many management practices to preserve soil, such as:Wind breaks – Planting trees in lines along crop fields to reduce wind erosion Contour farming – Orienting crop rows perpendicular to the natural slope of the land to reduce water erosion Conservation tillage – Preserving crop residue on the surface of the i elds and reducing the number of tillage operations- i.e., decreasing the numberof times i elds are cultivated to control weeds or plowed to disturb the soil.
Through the years, erosion-control methods have remained fundamentally important to cotton growers to protect the soil surface and manage the inl uence of water and wind.The implementation of erosion-control methods is not only vital in maintaining agricultural viability, but also is in the best interests of cotton growers for i nancially sound economic development and sustainability for the generations ahead. The cost to replace soil functions and remedy off-site damage due to soil erosion has been estimated at $19 per ton of soil; however, the cost caused by productivity losses is even greater.
Conservation Tillage: preventing erosion and improving soil quality
In agriculture production, the two guiding principles of soil preservation are: 1) minimize topsoil lost to erosion; and 2) improve soil health. Typically, both of these objectives are accomplished by increasing organic matter with winter/cover crops and minimizing the amount of tillage used on the soil.
To control weeds and diseases, traditionally producers were forced to remove all plant residues and weeds from the soil surface prior to planting, and then continue to cultivate the soil while the crop was growing to control late emerging weeds. While tilling does control some disease and weeds, it also loosens the soil !- Today, thanks to seed treatment fungicides, herbicides and herbicide tolerant cotton, diseases and weeds can be controlled without tilling, allowing what is referred to as “no-till” an conservation tillage systems to be adopted.
Cotton has made great strides in reducing tillage and using winter, or cover, crops. The number of acres of cotton produced with reduced-tillage systems has been increasing for the last 10 years. In addition to preserving the soil, reducing tillage signii cantly reduces fuel use and its associated cost to growers.
Sustaining Soil Fertility
In addition to carbon dioxide, water and sunlight, all plants need mineral nutrients to grow. The primary nutrients are nitrogen, phosphorus, and potassium. Other secondary and micronutrients also play a role.
There are various methods to meet the fertility requirements of cotton, including the use of nitrogen-fixing cover crops, manures and soluble fertilizers. While alternative sources to soluble fertilizers may seem a sustainable solution, relying on them as a sole source of fertility can compromise yields or lead to the leaching and runoff of nutrients, because the timing that will impact the release of the nutrient to the plant has a high level of uncertainty.
Excess Nitrogen is particularly prone to leaching and runoff and has become a water-quality concern for agriculture. For cotton producers, this is a fiber quality, financial and an environmental issue. Excess Nitrogen delays harvest which generally reduces i ber quality. Nitrogen that leaves the i eld does not get used by the plant and becomes, literally, money down the drain. Nitrogen contamination is a real concern, and highly advanced scientii c calculations are used to practice the most accurate application of this element.
Modern Production Practices Preserve Soil Resources
In addition to the tremendous progress that has been made in reducing tillage operations and encouraging organic matter increase in the soil, other modern technologies are also being used to detect and manage crop nutrient needs, including Global Positioning System (GPS) receivers, multi-spectral images and ground-based sensors to map out soil property variations in the i eld.
The use of these combined technologies is often referred to as “precision” or “site-specific”agricultural management -precisio for short. Although basic soil properties, such as soil texture, cannot be changed outright, more accurate and advanced measurements leads to increased efficiency and productivity. Today, almost 73% of U.S. cotton growers indicate that they employ some type of precision technology in their management, with most reporting that they use it for the site-specii c application of soil nutrients.
One precision ag approach is to use a ground-based sensor (such as an electrical conductivity, or EC, sensor) to map the variability present in soil type within the i eld.
The Veris Electrical Conductivity Sensor is a modern agricultural tool that is used to test soil electrical conductivity and soil texture, a factor which has a major impact on agricultural productivity, including water holding capacity, topsoil depth, and nitrogen-use efficiency.
This is an effective way to map soil texture because smaller soil particles such as clay conduct more current than larger silt and sand particles. Soil EC measurements have been used since the early 1900s, and the process is now mobilized and aided by GPS.
As the cart containing the EC sensor is pulled through the field, one pair of coulter-electrodes injects a known voltage into the soil, while the other coulter-electrodes measure the drop in that voltage.
The result is a detailed map of the soil texture variability that guides growers’s crop selection and zones. Soil samples are taken to analyze the nutrient need of each soil type present. Once the map is created, it is loaded into the fertilizer applicator controller and then each soil type receives only the amount of nutrient that is required in that area of the field. This insures over-application does not occur and assures that crop needs are met.
The latest research effort is focusing on the use of sensors to detect the condition of the crop and vary the amount of nutrient applied in i elds in real time. This eliminates the time spent creating and loading maps, and will provide even greater precision by letting the plant signal its individual needs.
Cotton is able to thrive in marginal soils
Uninformed observations about cotton planting and soil fertility in the U.S. led to the erroneous conclusion that cotton production decreased the fertility of the soil upon which it was planted. The myth of cotton being “hard on the soil” or “a heavy user of soil nutrients” derives from two long-standing and appropriate farming practices: the selection of crops suited for specii c soils and the allocation of limited resources to maximize economic return.
During the 1800s the limited distribution capability of agricultural commodities dictated that each farm produce a diverse array of crops to meet the local food needs, to feed the livestock needed for tilling the soil, and to generate income. Thus, farms would plant a mixture of pasture crops, vegetable crops, grain crops and cash crops.
The cotton plant was well known at the time to be tolerant of soil infertility and its seed to be of high value as a fertilizer. Thus, presented with an array of soil types and limited fertilizer resources, cotton was planted on the least fertile ground and its nutrient-rich seed, after being separated from the lint at the gin, was applied as a fertilizer to other crops, either directly or after being fed to livestock.
Over time this practice depleted the i elds of nutrients that were planted on marginally fertile lands only with cotton, which further restricted the planting of higher-fertility demanding crops on these fields. To the casual observer, not familiar with farming practices, it appeared that cotton was “hard on the soil.”
Source form China Textile Magazine
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