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Dryland farming anddry farming encompass specificagricultural techniques for thenon-irrigated cultivation ofcrops. Dryland farming is associated withdrylands, areas characterized by a coolwet season (which charges the soil with virtually all the moisture that the crops will receive prior to harvest) followed by a warm dry season. They are also associated witharid conditions, areas prone todrought and those having scarce water resources.
Dryland farming has evolved as a set of techniques and management practices to adapt to limited availability of water, as in the Western US and other regions affected byclimate change for crops such astomato andmaize.[2]
In marginal regions, a farmer should be financially able to survive occasional crop failures, perhaps for several years in succession. Survival as a dryland farmer requires careful husbandry of the moisture available for the crop and aggressive management of expenses to minimize losses in poor years. Dryland farming involves the constant assessing of the amount of moisture present or lacking for any given crop cycle and planning accordingly. Dryland farmers know that to be financially successful they have to be aggressive during the good years in order to offset the dry years.
Dryland farming is dependent on natural rainfall, which can leave the ground vulnerable todust storms, particularly if poor farming techniques are used or if the storms strike at a particularly vulnerable time. The fact that afallow period must be included in thecrop rotation means that fields cannot always be protected by acover crop, which might otherwise offer protection againsterosion.
Some of the theories of dryland farming developed in the late 19th and early 20th centuries claimed to be scientific but were in realitypseudoscientific and did not stand up to empirical testing. For example, it was alleged thattillage would seal in moisture, but such "dust mulching" ideas are based on what people imagineshould happen, or have been told, rather than what testing actually confirms. In actuality, it has been shown that tillage increases water losses to evaporation.[3] The bookBad Land: An American Romance explores the effects that this had on people who were encouraged tohomestead in an area with little rainfall; mostsmallholdings failed after working miserably to cling on.
Dry farming depends on making the best use of the "bank" of soil moisture that was created by winter rainfall. Some dry farming practices include:[4][5]
Dry farming may be practiced in areas that have significant annual rainfall during a wet season, often in the winter. Crops are cultivated during the subsequent dry season, using practices that make use of the stored moisture in the soil.California,Colorado,Kansas,South Dakota,North Dakota,Montana,Nebraska,Oklahoma,Oregon,Washington, andWyoming, in theUnited States, are a few states where dry farming is practiced for a variety of crops.[4][6]
Dryland farming is used in theGreat Plains, thePalouse plateau ofEastern Washington, and other arid regions of North America such as in theSouthwestern United States andMexico (seeAgriculture in the Southwestern United States andAgriculture in the prehistoric Southwest), the Middle East and in othergrain growing regions such as thesteppes of Eurasia andArgentina. Dryland farming was introduced to southern Russia and Ukraine byUkrainian Mennonites under the influence ofJohann Cornies, making the region thebreadbasket of Europe.[7] In Australia, it is widely practiced in all states but theNorthern Territory.
The choice of crop is influenced by the timing of the predominant rainfall in relation to the seasons. For example, winter wheat is more suited to regions with higher winter rainfall while areas with summer wet seasons may be more suited to summer growing crops such assorghum, sunflowers orcotton.[8] Dry farmed crops may includegrapes,tomatoes,pumpkins,beans, and other summer crops.
Dryland grain crops include wheat, corn, millet, rye, and other grasses that produce grains. These crops grow using the winter water stored in the soil, rather than depending on rainfall during the growing season.[4]
Successful dryland farming is possible with as little as 9 inches (230 millimetres) of precipitation a year; higher rainfall increases the variety of crops.
In regions such asEastern Washington, the average annual precipitation available to a dryland farm may be as little as 220 millimetres (8.5 in).[9] In theHorse Heaven Hills in central Washington, wheat farming has been productive purportedly on an average annual rainfall approaching 6 inches.[10] Consequently, moisture must be captured until the crop can utilize it. Techniques includesummer fallow rotation (in which one crop is grown on two seasons' precipitation, leaving standing stubble andcrop residue to trap snow), and preventingrunoff byterracing fields. "Terracing" is also practiced by farmers on a smaller scale by laying out the direction of furrows to slow water runoff downhill, usually by plowing along eithercontours orkeylines. Moisture can be conserved by eliminating weeds and leaving crop residue to shade the soil.
Once moisture is available for the crop to use, it must be used as effectively as possible. Seed planting depth and timing are carefully considered to place the seed at a depth at which sufficient moisture exists, or where it will exist whenseasonal precipitation falls. Farmers tend to use crop varieties which aredrought-tolerant and heat-stress tolerant (even lower-yielding varieties). Thus the likelihood of a successful crop ishedged if seasonal precipitation fails.
The nature of dryland farming makes it particularly susceptible to erosion, especially wind erosion. Some techniques for conserving soil moisture (such as frequent tillage to kill weeds) are at odds with techniques for conserving topsoil. Since healthytopsoil is critical tosustainable agriculture, in particular within arid areas, its preservation is generally considered[citation needed] the most important long-term goal of a dryland farming operation.Erosion control techniques such aswindbreaks,reduced tillage orno-till, spreading straw (or othermulch on particularly susceptible ground), andstrip farming are used to minimize topsoil loss.
Weedling is process of turning over 90 degree and exposing weed's root during tillage to prevent soil erosion by wind anddesertification. At the same time, Direct absorption of nutrients from weeds and moisture provides suitable environment to floris biodiversity of organisms in soil.
Dryland farming is practiced in regions inherently marginal for non-irrigated agriculture. Because of this, there is an increased risk ofcrop failure and poor yields which may occur in a dry year (regardless of money or effort expended). Dryland farmers must evaluate the potential yield of a crop constantly throughout the growing season and be prepared to decrease inputs to the crop such as fertilizer andweed control if it appears that it is likely to have a poor yield due to insufficient moisture. Conversely, in years when moisture is abundant, farmers may increase their input efforts and budget to maximize yields and to offset poor harvests.
Arid-zone agriculture, or desert agriculture, is the subject of research and development that includes studies of how to increase the agricultural productivity of lands dominated by a lack of fresh water, an abundance of heat and sunlight, and usually one or more of the following: Extreme winter cold, short rainy season, saline soil or water, strong dry winds, poor soil structure, overgrazing, limited technological development, poverty, or political instability.[citation needed]
The two basic approaches are:[citation needed]
Media related toDryland farming at Wikimedia Commons
