Tillage methods

Incorporation of plant residues using an inverting plough is known to be the most efficient tillage method of reducing levels of Fusarium inoculum on the soil surface, the incidence of FHB and DON levels in wheat, especially... 

Dao, T.H. (1995). Subsurface mobility of metribuzin as affected by crop residue placement and tillage method. J. Environ. Qual., 24 1193-1198. 

On farms practicing no-till com production, herbicides are the main tool for weed control. Without herbicides, notill farmers would have to switch to some other form of tillage operation. They could no longer use no-tillage methods, resulting in much more soil erosion. Triazine and other herbicides in com will continue to represent the main weed control technology for the vast majority of com acreage. 

The impact of herbicides on our modern agricultural technology has been phenomenal. It is almost impossible to measure or to overemphasize the importance of herbicides in their potential for overcoming famine, pestilence, poverty and crop losses due to weeds that were prevalent throughout most of the history of mankind prior to the 1950s. Herbicides have been essential, not only for their direct effects on weed control and crop yield, but also in providing more efficient use of water and fertilizers for the optimum development of improved crop varieties and hybrids. They have also been essential tools in the recent development of conservation tillage methods, which have reduced topsoil erosion and moisture losses in many areas of the world. 

Eghball, B., L.N. Mielke, G.A. Calvo, and W.W. Wielhelm. 1993a. Fractal description of soil fragmentation for various tillage methods and crop sequences. Soil Sci. Soc. Am. J. 57 1337-1341. 

The use of spoils for the growing of rotation crops or fruit trees necessitates that the area be graded to a slope not greater than about 10%, unless erosion is to be controlled by the use of hay crops, terraces, and minimum tillage methods. It is also essential that few resistant rocks be present in the surface one foot. Since the presence of any appreciable amount of non-disintegrating surface rocks ehminates the spoil bank as a medium for the growth of cultivated crops, it is obvious that few spoil banks can be utilized for this purpose. 

Some of the minimum tillage methods that are becoming popular in the United States are highly effective in erosion control. For row crops that are suited to this type of culture, the soil is disturbed very little and the crop residues remain in place. This system favors good aggregation, high infiltration, minimum runoff, and little loss via winds. 

KLEIN T.M. and KOTHS J.S. 1980. Urease, protease and acid phosphatase in soil continuously cropped to corn by conventional or no-tillage methods. Soil Biology and Biochemistry, 1, 293-294. 

An annual estimated cost of approximately 938,835,000 is required for labor and equipment to apply 204.5 million kilograms of herbicides to 147.6 million hectares of cropland in the United States (Table IV). Mechanical tillage to control weeds between cropping seasons and interrow tillage of crops has been used for centuries as a very effective method of weed control. Approximately 50% of all tillage between crops is done to control weeds. The number of cultivations required for effective weed control within a row crop varies from two to five during a cropping season. 

In two different soils under lab conditions, where the pHs were 4.8 and 6.5, respective halfllves of 45 days and 113 days were found (52). The half-life under field conditions Is <1 month but hydroxysImazlne, the major degradation product, may persist (106). The more acidic the soil, the more rapid Is the hydrolytic reaction forming hydroxysImazlne (107). Persistence of slmazlne Increases as soil pH Increases, with maximum persistence at a pH of 6.6, and It Is affected by the method of tillage (108). 

Pratley, J.E. 2000. Tillage and other physical management methods. In Sindel, B. (ed.) Australian Weed Management Systems. R.G. and F.J. Richardson, Melbourne, pp. 105-122. 

Shorter fallow periods store precipitation more efficiently for several reasons. First, water is stored more readily when soils are dry, early in fallow periods, than later in fallow periods when soils are wetter. Secondly, when plant residues are preserved with no-till methods, water infiltration is encouraged and runoff and evaporative losses are reduced as compared to tilled soils with less residue. Indeed, mechanical tillage within fallow periods practically assures soil water loss as soils dry out and warm up in the tilled zone. 

Historically, tillage and hand weeding were the main methods of weed control. Since the advent of herbicide use in 1950, essentially all sugarcane in Australia now receives one or more herbicide applications. Virtually all of the crop is produced on family-operated, commercial-scale farms and is processed at cooperative or privately owned mills. 

---