Crop rotation
Under rotation or field system the temporal sequence of on a will agricultural cultivated crop species in the flow area of the vegetation period understood and years. In contrast, in single-field farming or monoculture , no crop rotation takes place over a period of 5 years. In Central Europe , rye was mostly grown on these arable land for several years in a row.
The crop rotation is intended to sustainably renew and maintain soil fertility. It is an important part of modern agricultural management in conventional as well as ecologically oriented farming. In principle, crop rotations are differentiated according to their organizational form.
Emergence
Doubt of the economy in antiquity
In ancient and early medieval agriculture, the Doubt derwirtschaft was common, in which the arable land was divided into two fields, one of which was tilled with grain , while the other lay fallow. As a result, in comparison to three-field farming, half instead of a third of the usable area was fallow. Alternatively, one could cultivate one field with summer and the other with winter grain, but the soil was heavily used.
Change of country was the reason for many clearings . In addition, it often prevented farmers from settling down and led to the way of life of shifting farming .
Three-field economy in the Middle Ages
The three-field economy was the form of agriculture that had been widespread in Europe since the Middle Ages around 1100 AD . The Romans were already familiar with the Doubt derwirtschaft (“Landwechsel”) and also used it north of the Alps. In the High Middle Ages , starting from Carolingian monasteries , after the introduction of the new equipment of the 11th century, the three-field system was introduced across the board.
In the yearly change were
- a field with the winter grain sown before winter (then rye and emmer ) and
- a second one with the summer cereals sown after winter ( oats , millet , barley ).
- The third field remained fallow this year , so the soil here could recover. However, it served as a pasture for cattle .
The Flurzwang prescribed the crop rotation for the farmers. The three-field economy meant a significantly higher yield compared to the previous form of cultivation, the change of country. In addition, it enabled regulated ownership.
Beginning of modern agriculture
In the middle of the 18th century the medieval three-field economy and the history of modern agriculture began to be overcome . For example, a start was made to use red clover for the targeted cultivation of fodder crops in the fields and thus to produce higher-quality fodder for the cattle. Johann Christian Schubart Edler von Kleefelde was one of the German pioneers in this field. The introduction of the potato in Germany as a root crop and food crop also contributed to the expansion of crop rotations. At the end of the 18th century, Albrecht Daniel Thaer founded scientific farming and also advocated this system. He saw in extensive arable forage cultivation the possibility of promoting soil fertility both through the residues of the arable forage plants and through targeted fertilization with manure and to increase the humus in the fields. Thus began a step-by-step intensification of agriculture and with it a variable crop rotation economy, which was based on natural and operational requirements and broke up the rigid systems of the past.
Today, crop rotation is an important part of agriculture and modern agricultural management, both in conventional and organic farming. It gives farmers a certain degree of flexibility in the marketing of their products, protects the soil structure, prevents, for example, erosion and saves costs for pesticides and fertilizers. Crop rotation is often seen as an important component on the way to sustainable and soil-conserving agriculture.
Today there is also a concentration of monocultures worldwide, for example in the cultivation of genetically modified soy or corn in South America and the USA . This is largely achieved through resistance to total herbicides or pests. The individual cultivation of self-succession over several years, i.e. the three to five cultivation of the same crops, for example maize, is now common practice and is often criticized.
Advantages and disadvantages
The cultivation of different plants leads to a differentiated build- up and breakdown of the nutrients contained in the soil and can lead to an increase in the humus content with sensible crop rotations , whereby they are preserved in the long term. A sensibly designed crop rotation also reduces the infestation of the crops with plant diseases and some animal pests . Furthermore, weeds are less able to get out of hand if the crops grown are changed. They are particularly disturbed by the different types and times of tillage.
Many fungal diseases in cereals can survive on remains of straw and weeds in the soil and require a break in cultivation of 1 to 2 years for cereals. They have a particularly negative effect on the yield of (winter) wheat and sometimes cause the grain to be in the wrong position, i.e. the stalks break and the grain kinks. Other types of grain such as B. Oats and (summer) barley are less sensitive, oats also count as a fruit of recovery within the crop rotations that are strongly dominated by grain. Therefore, the three-field economy began with the very vulnerable winter wheat, followed in the second year by a summer cereal such as oats. In the third year, the cultivation of root crops had an even more favorable effect than the fallow land, as the intensive tillage (hoeing for weed control) brought a lot of air into the soil. As a result, straw residues with fungal spores were better broken down.
This results in yield security and an increase in yield (e.g. when switching from two to three field farming this was around 20%). Another advantage of crop rotations is the possibility of using deep-rooted plants such as rape or alfalfa to transport nutrients upwards from the deeper soil layers and make them available for subsequent crops. Another advantage is that damaging compaction can be broken up and reduced.
The permanent vegetation of the arable land reduces erosion and strengthens the soil structure and the soil fauna and flora. As a result, a better water and air balance is established in the soil and thus a better nutrient availability is achieved. Crop rotations increase flexibility in the marketing of agricultural goods, secure yields and save the use of pesticides and synthetic fertilizers. In particularly good soils such as black earth, they ensure that soil fertility is maintained. In poor soils with an unfavorable water balance, such as sandy soils, they ensure better soil fertility and a significant increase in yield.
The disadvantages of crop rotation are mostly due to economic factors: Crop rotations make special demands on agricultural management. For example, potatoes and sugar beet require completely different storage machines and techniques than grain. Nowadays, not all farms have animals, which means that the cycle of animal husbandry and crop cultivation that was envisaged at the time can only be implemented to a limited extent. Targeted fertilization with animal fertilizers (liquid manure, liquid manure, manure) is often more difficult than with synthetic or mineral fertilizers. The use of forage plants is therefore not always guaranteed. Catch crop cultivation is usually more expensive than the use of pesticides, but it saves fertilizer and secures the soil structure.
Regular control of the humus content and a humus balance are very useful for good crop rotation management. Although they mean more effort, they can also enable funding within the EU's cross compliance regulations.
Crop rotation system
Within the crop rotation, a distinction is made between root crops (e.g. beets, potatoes, rapeseed, silage maize), stalk crops (grain) and catch crops, which in turn are divided into summer and winter catch crops (e.g. mustard, sunflowers, etc.). Culms are often called humus consumers and leaf crops as humus multipliers. This division was developed on the one hand by the harvest residues, the rooting and the tillage. However, all fruits have different properties, as a result of which they remove or add nutrients to the soil and improve or worsen its properties. Fruit-specific fertilization, such as rapeseed (rich in nitrogen), can also play an important role in shaping the following crops. Catch crops are incorporated into the soil without being harvested and have a variety of functions, e.g. B. to break up damaging compaction, to keep or return nutrients for the subsequent crop, to stabilize the soil structure, but also to kill pests.
When designing the crop rotation, particular attention should be paid to the timing of the plant population. The carbon-nitrogen ratio is decisive for the decision as to which foliage and semicircular crops are used. It decides how quickly the crop residues can be converted by the soil organisms. The following applies here: the more nitrogen, the faster residues are fed into the soil. Legumes ( lupins , alfalfa or clover ) are particularly suitable for this . They have nitrogen-fixing bacteria in their roots and are therefore very well suited to increasing soil fertility. Since some of them are perennial, it is possible to use a jumping stroke. This means that alfalfa, for example, is grown on a field within the crop rotation, which is on the field for around three to four years and is used for harvesting forage crops. After that, wheat or similar crops can be grown again.
Today crop rotations are variable, depending on the requirements of the farm, and are by no means rigid. However, they can be divided into leaf and culm crops according to the number of cultivated fields or the arrangement.
Three-field economy
The three-field crop rotation consists of three crop rotation fields. A specific crop is grown for each crop rotation field within a year. This crop rotation places a high emphasis on stalk crops.
The crop rotation fields are arranged as follows:
- Leaf fruit (e.g. rapeseed)
- Straw fruit (e.g. wheat)
- Straw fruit (e.g. rye)
Four-field economy
The four-field economy consists of four crop rotation fields. It is strongly dominated by strawberries and is classified as follows:
- Leaf fruit (e.g. rapeseed or sugar beet)
- Culm crop (e.g. wheat with a summer catch crop)
- Straw fruit (e.g. oats or barley)
- Straw fruit (e.g. winter rye or triticale)
Rhenish crop rotation
The Rhenish crop rotation consists of five crop rotation fields. The leaf crop / stalk crop ratio is 40:60. Here, too, there is a dominant position of crops.
The crop rotation elements are arranged as follows:
- Leaf fruit (e.g. potatoes, beets, rape)
- Culm crop (e.g. winter rye, winter barley, winter wheat)
- Straw fruit (e.g. winter barley)
- Leaf crops (e.g. summer catch crops and silage corn)
- Straw fruit (e.g. spring barley, oats)
Crop rotation economy
The crop rotation economy has the most favorable leaf crop / stalk crop ratio. Here leaf fruits and stems change every year, so that a ratio of 50:50 arises.
Accordingly, the design is as follows:
- Leaf fruit (e.g. sugar beet)
- Straw fruit (e.g. spring barley)
- Leaf fruit (e.g. field beans)
- Culm crop (e.g. winter wheat / summer catch crop)
Double crop economy
In the double fruit economy, leaf crops and stems are also alternated. However, two leaf fruits alternate with two stem fruits. Here it is particularly important to ensure that the leaf fruits are mutually compatible. This also applies to the leaf fruits, for example rapeseed and sugar beets should never be grown one after the other, as they are both susceptible to different nematodes and pests that attack both rapeseed and sugar beet. In the case of crops, this applies, for example, to spring barley and winter barley. Compliance with the cultivation breaks is very important. Rye and corn are often self-tolerating. However, they should not be grown longer than twice in a row, as otherwise problems such as increased infestation by fusaria in maize or ergot in rye can occur.
The introduction:
- Leaf fruit (e.g. chickpeas)
- Leaf fruit (e.g. winter rape)
- Strawberry (e.g. winter wheat)
- Culm crop (e.g. winter barley / summer catch crop)
Or alternating: (intensive use without catch crops)
- Leaf fruit (e.g. sugar beet)
- Strawberry (e.g. winter wheat)
- Leaf fruit (e.g. potatoes)
- Culopus (e.g. winter / spring barley, winter wheat or winter rye)
Overcrop cropping
Over crop rotation has a higher proportion of leaf crops. It can be divided into:
- Leaf fruit (e.g. potatoes)
- Leaf fruit (e.g. field vegetables)
- Strawberry (e.g. winter wheat)
- Leaf fruit (e.g. chickpeas)
- Leaf fruit (e.g. winter rape)
- Straw fruit (e.g. winter barley)
Typical phytopathogens that can be regulated by crop rotation
Failure to comply with crop rotation and failure to comply with cultivation breaks favor soil-borne pathogens ( phytopathogens , see also: crop rotation pathogens ). This is primarily due to the fact that their chances of survival in the soil and on crop residues are much higher over a maximum of one winter than over several years with changing crop rotations. The one-sided deprivation of nutrients can also weaken the crop population and thus favor fungi and other plant diseases.
Examples:
- Strawberry disease
- Black-leggedness
- Nematodes (e.g. beet cysts)
- Rust fungi
- Fusaria
- Ergot
Typical weeds that can be regulated by crop rotation
If there is no crop rotation, the accompanying field flora, which is adapted to the crop, is promoted, i.e. the weeds, which have better opportunities to spread due to the continuous conditions over the years. Effective crop rotation management can regulate the spread of accompanying flora, as allelopathic effects and competition between crops vary due to the change in crops; This results in a different socialization of the species within the agricultural ecosystem, and weeds are suppressed.
Examples:
See also
literature
- Wulf Diepenbrock, Frank Ellmer, Jens Léon: Arable farming, crop production and plant breeding . Ulmer, Stuttgart (Hohenheim) 2012, ISBN 978-3-8252-3843-8 .
- Matthias Preissner: The contribution of crop rotation in organic farming to the sustainable usability of the natural balance . Edition Zukunft, Barsinghausen 1988, ISBN 3-89799-077-6 .
- Bernhard Freyer: Crop rotations . Ullmer, Stuttgart (Hohenheim) 2003, ISBN 3-8001-3576-0 .
Web links
- Cross compliance regulations
- Definition of crop rotation at Meyers Lexikon Online ( Memento from December 28, 2007 in the Internet Archive )
- oekolandbau.de: Crop rotation in organic farming
Individual evidence
- ↑ Diepenbrock et al .: Crop rotations In: Ackerbau, Pflanzenbau, Plant Breeding No. 3, 2012, pp. 35–36.
- ↑ Diepenbrock et al .: Historical Development In: Ackerbau, Pflanzenbau, Plant Breeding No. 3, 2012, p. 34.
- ↑ Paying agency director of the North Rhine-Westphalia Chamber of Agriculture as state representative: Maintaining agricultural land in good agricultural and ecological condition In: Information on compliance with other obligations (Cross Compliance) No. 1, 2013, pp. 1–5.
- ↑ Diepenbrock et al .: Crop rotation systematics In: Ackerbau, Pflanzenbau, Pflanzenzüchtung No. 3, 2012, pp. 37–46.