Cultivation = the overturning of the soil prior to planting, and/or between growing plants. Its primary purposes are to clear the soil of existing plant material (clean cultivation) and establish a uniform planting bed, or for a growing crop to remove weeds and improve aeration.
Negative effects: clean cultivation can lead to increased soil moisture loss, increased wind or water erosion, and increased machinery compaction if the soil is moist and high in clay.
Harbor Street,
Ephesus, Turkey. Only 2000 years ago, Harbor St. ended at the wharves of one of the
great ports of the Roman Empire. The bay has since filled in due to
erosion-promoting agricultural practices in the surrounding hills, so the Aegean Sea is
now several miles away.
Reduced or no-till cultivation is a possible alternative to solve the above problems. However, no-till can result in increased pesticide/herbicide use and increased disease problems due to pathogen overwintering in stubble.
Cultivation methods include plowing, disking, rototilling, and harrowing. Harrowing is a typical post-planting weed control method. A popular method of clear cultivation in forested regions of the developing world is slash-and-burn, or milpa, cultivation (shown below). This method converts nutrients from the forest canopy into ash to fertilize the soil, at the same time releasing tremendous amounts of carbon-laden smoke into the atmosphere. It also exposes bare soil to water erosion.
Burning vegetation
for milpa agriculture in rainforests along the Petexbatun River, northern Guatemala.
Cropping strategies include yearly rotation, succession cropping (multiple crops per year), intercropping (two crops in a field at the same time), and mulching. Rotation prevents the chronic buildup of crop-specific pest/insect populations and it can improve soil structure and fertility (if a legume is included in the rotation). Succession cropping is a strategy to maximize production in a given garden or field, and may require high fertilizer and pesticide inputs. Intercropping requires considerable knowledge and attention due to potential difficulties with crop competition, allelopathy, and pest or disease buildup. Mulching is a very good way to control erosion, minimize freeze damage, retain soil moisture, and prevent weed problems.
Broomcorn
intercropped with sesame, okra, and chickpeas in a traditional Arab family plot, Lower
Galilee, Israel.