No tillage systems

Developing no-tillage systems without chemicals the best of both worlds ... 

Figure 16.4. SFR concentration of SOM in the 53-20-, 20-2- and <2-pm-sized organo-mineral complexes from a 0- to 25-mm layer of an acrisol under conventional and no-tillage systems. Reprinted from Bayer et al. (2002b).

Downward movement of triazines may occur from percolating water carrying them to lower soil depths. Within well-structured soils with abundant macropores, triazines have been reported to move to deeper depths than in nonstructured soils with fewer pores. Increased permeability, percolation, and solute movement can result from increased porosity -especially in no-tillage systems where there is pore connectivity at the soil surface. Triazines can move to shallow ground-water by macropore flow in sandy soil if sufficient rainfall occurs shortly after they are applied (Ritter et al, 1994a, b). 

For pesticides to leach to groundwater, it may be necessary for preferential flow through macropores to dominate the sorption processes that control pesticide leaching to groundwater. Several studies have demonstrated that large continuous macropores exist in soil and provide pathways for rapid movement of water solutes. Increased permeability, percolation, and solute transport can result from increased porosity, especially in no-tillage systems where pore structure is still intact at the soil surface (70). Plant roots are important in creation and stabilization of soil macropores (71). 

In the no-tillage system, a cover crop can be used to suppress weeds. Sites are covered with some plant residue, which reduces soil erosion and improves water retention. Crop seeds are drilled into the soil through the sod or previous crop residues and the cover. The cover crop may be killed by overwintering or with a contact herbicide. Potential cover crops include barley, rye, sorghum, buckwheat, sudangrass, sweetclover, and sunflower. All have been reported as allelopathic to test species (Rice 1984). Putnam s group examined several species including rye, Secale cereale. 

Crambe could be cultivated as a cover crop. The decomposition and nutrient release from crop residues of crambe in the implementation of no-tillage system has been reported. Heinz et al. (2011) have reported that the kinetics of residue decomposition in crambe were similar to those of nutrient release with an initial rapid phase followed by a slower one. K, P, and Mg are released more quickly for subsequent crops, while the increased speed of nutrients release occurred around 15 days after the biomass management. Due to a high content of glucosinolates, crambe could also be used as a crop for biofumigation. 

CHC, Conservation Technology Information Center (1998). Available at http //www.ctic.purdue.edu Diaz-Zorita M, Duarte G, Grove J (2002) A review of no-till systems and soil management for sustainable crop production in the subhumid and semiarid Pampas of Argentina. Soil Tillage Res 65 1-18... 

Barnes JP, Putnam AR (1983) Rye residues contribute weed suppression in no-tillage cropping systems. J Chem Ecol 9 1045-1057... 

In the direct drilling (no-till seeding) practice in the united Kingdom/ straw residues from the preceding crop are usually burnt because poor crop establishment and yields can result/ particularly on heavy soils in wet years (10). Similar problems can occur in the conservation tillage systems oF the Pacific Northwest (L.F. Elliott and H.-H. Cheng/ this volume). 

Abdul-Baki, A.A. and Teasdale, J.R. 1993. A no-tillage tomato production system using hairy... 

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