Crop Rotation

Crop Rotation - Why is it important?

• The term cropping system or crop rotation refers to the crops and crop sequences and the management techniques used on a particular field over a period of years.
• Crop rotation, as a rule, improves performances of each crop: this is consequent to different nutrition and tillage requirements by different crops.
• Rotation allows to spread operations in different seasons of year, which easiest management of farms concerning labor and operational loads.
• Cash flow is spread on different season, thus decreasing risks bound with negative meteorological factors.
• Exploitation of soil physical and chemical fertility is improved, as different crops roots explore different layers of soil: also different crops use different amounts of nutrients and require different tillage depths.
• Structure of soils improves, because residues from crop roots stay at different depths and residues are also different in chemical composition.
• Weeds, pests and diseases management gets easier because different crops have different pests and weeds, on which different chemicals are used: as a whole, pests and weeds are more easily managed.
• Fallow can enter in rotation with other crops: such a practice is still spread in many areas of dry wheat cropping in order to re-build fertility of soils.

Cash crops system: sufficient water available

Precipitations or irrigation

• This is a typical example of crops with different requirements concerning nutrition and tillage: sugar beet is more demanding for P and K, and requires deeper tillage practices, when corn and wheat are more demanding for N and can be cropped with less expensive tillage systems. Soybean, if properly grown, does not requires N, conversely increases the content of soil in N through symbiosis with fixing N Azotobacter strains.
• Weed control in these crop is also different: in sugar beet and soybean grass weeds are easy to control, when broad leaves are difficult: the contrary for corn and wheat. So, by rotating the crops, the results of weeds control improves significantly.
• Different strains of fungi damage these crops, so such a sequence makes more difficult the building up of spores in the soil: as a result, the pathogens’ pressure on crops decreases during the years. This is (relatively) true also for insects’ pressure.
• Life cycles of different plants are different, so field operations are spread on a broader period. Timeliness of operations and distribution of workloads on machinery during the season improves.
• Tillage operation are deeper for sugar beet, when minimum tillage can be applied for other crops: the overall results is an improved soil tilth, due to different working depths.

Flexible cash crop system: dryer conditions, moisture is a concern

• In these examples, crops that are more resistant to drought (sunflower, sorghum, chickpeas and alfalfa) have substituted crops requiring higher levels of moisture in the soil (sugar beet, corn, soybean). Obviously, “resistant to drought” means that such crops are able to wait for water longer than other crops, or have physiological mechanism for consuming less moisture.
• Legumes are anyway present in rotation, both for grain production (peas) and forage production (alfalfa).
• Introducing of fallow (set aside) can be a good solution in extensive conditions, where inputs as fertilizers and chemicals are not available in full size, mechanization is not totally sufficient and/or acreages are very large.
• Fallows also allows both mechanical and chemical weeds control and thus the building up of soil moisture, which becomes available for the following crop.