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Data extracted in Sept 2021 September 2021
Fiche created in February 2024

Note to the reader: This general fiche summarises all the environmental and climate impacts of CROP ROTATION found in a systematic review of 17 synthesis research papers[1]. These papers were selected from an initial number of 248 yielded by 249 obtained through a systematic literature search strategy, according to the inclusion criteria reported in section 4.  The impacts reported here are those for which there is scientific evidence available in published synthesis papers, what does not preclude the farming practice to have other impacts on the environment and climate still not covered by primary studies or by synthesis papers.

The synthesis papers review a number of primary studies ranging from 3 to 122. Therefore, the As each synthesis research paper involves a number of primary research papers ranging from 3 to 122, the assessment of impacts relies on a large number of results from the primary studies, obtained mainly in field experiments (carried out in situations close to real farming environment).  conditions, or sometimes in lab experiments or from model simulations.

1.     DESCRIPTION OF THE FARMING PRACTICE

...

• Description:
  • Crop rotation on arable land is the practice of alternating crops grown on a specific field in a planned pattern or sequence in successive crop years, so that crops of the same species are not grown without interruption on the same field. In a rotation, the crops are normally changed annually, but they can also be multi-annual. If the same crop is grown continuously, the term monoculture can be used to describe the phenomenon[2].

...

• Key descriptors

...

• :
  • This

...

• • review includes three types of crop rotation comparisons²: (i)

...

• •  rotations of two crops compared to monocropping[3] (in

...

• • 10 synthesis papers), (ii) rotations of 3 or more crops compared to monocropping (in

...

• • 2 synthesis papers), and (iii) rotations of 3 or more crops compared to crop rotation of two crops (in

...

• • 2 synthesis papers).

...

• • Seven synthesis papers did not clearly specify the type of rotation (more diverse rotations vs.

...

• •  monocropping or 2-crop rotation).

...

• • This

...

• • review does not

...

• • include synthesis research papers that study the primary effects of: (i)

...

• •  cover crops - plants that are cultivated to cover (and protect) the soil instead of being harvested (i.e., studies where cover crops were only present in the intervention group and not in the control, were excluded), (ii)

...

• •  break crops - alternative crops to interrupt the repeated sowing of a cash crop, and (iii)

...

• •  fallowing - leave the arable land without planting for at least one year. The direct impacts of these three practices are evaluated in separate sets of fiches. 
    
    

2.

...

    EFFECTS OF THE FARMING PRACTICE ON CLIMATE AND

...

ENVIRONMENTAL IMPACTS

We reviewed the impacts of more diverse rotation (with two or more crops) compared to monocropping or simpler rotations.   (table 1)

The table below shows the number of synthesis papers reporting positive, negative and no effect, based on the statistical comparison of the intervention and the control. In addition, we include, if any, the number of systematic reviews with statistical tests reporting i) a significant difference between the Intervention and the Comparator, that is to say, a significant statistical effect, which can be positive or negative; or ii) a non-statistically significant difference between the Intervention and the Comparator. In addition, we include, if any, the number of synthesis papers reporting relevant results but without statistical test of the effects (“uncertain”). The numbers between parentheses indicate the number of synthesis papers with a quality score of at least 50%. Details on quality criteria can be found in the . Details on the quality assessment of the synthesis papers can be found in the methodology section of this WIKI. 

 Out Out of the 17 selected synthesis papers selected, 8 reported included studies conducted in Europe.  

It should be noted that none of the 4 meta-analyses reporting impacts on crop yield included experiments conducted in Europe but rather in North America or China. Some of these analyses did not consider yields for all the crop species in the rotation, but only for one species (the main cash crop). 15 synthesis papers out of 17 had a quality score higher than or equal to 50%. Some synthesis papers reported more than one impact. 

...

Impact 

...

Positive 

...

Negative 

...

No effect 

...

Uncertain 

...

Decrease GHG emissions 

...

1 (1) 

...

1 (1) 

...

2 (2) 

...

0 

...

Decrease pests and diseases 

...

1 (1) 

...

0 

...

1 (1) 

...

0 

...

Increase soil biological quality 

...

5 (5) 

...

0 

...

2 (2) 

...

0 

...

Increase soil nutrients 

...

2 (2) 

...

0 

...

0 

...

0 

...

Increase Carbon sequestration 

...

5 (3) 

...

1 (1) 

...

4 (2) 

...

0 

...

Increase Crop yield 

...

3 (3) 

...

0 

...

1 (1) 

...

0 

, and 15 have a quality score higher than 50%.

Table 1: Summary of effects. Number of synthesis papers reporting positive, negative or non-statistically significant effects on environmental and climate impacts. The number of synthesis papers reporting relevant results but without statistical test of the effects are also provided. When not all the synthesis papers reporting an effect are of high quality, the number of synthesis papers with a quality score of at least 50% is indicated in parentheses. Some synthesis papers may report effects for more than one impact, or more than one effect for the same impact.

3.     FACTORS INFLUENCING THE EFFECTS ON CLIMATE AND ENVIRONMENTAL IMPACTS

The factors significantly influencing the size and/or direction of the effects on the impacts, according to the synthesis papers included in this review, are reported below. Details about the factors can be found in the summaries of the meta-analyses available in this WIKI.

Table 2: List of factors reported to significantly affect the size and/or direction of the effects on environmental and climate impacts, according to the synthesis papers reviewed. The reference number of the synthesis papers where those factors are explored is given in parentheses.

4.    SYSTEMATIC REVIEW SEARCH STRATEGY

Table 3: Systematic review search strategy - methodology and search parameters.

3. SYSTEMATIC REVIEW SEARCH STRATEGY

4. LIST OF SYNTHESIS PAPERS INCLUDED IN THE REVIEW

5.     SYNTHESIS PAPERS INCLUDED IN THE REVIEW

Table 4: List of synthesis papers included in this review. More details can be found in the summaries of the meta-analyses.

Disclaimer: These fiches present a large amount of scientific knowledge synthesised to assess farming practices impacts on the environment, climate and productivity. The European Commission maintains this WIKI to enhance public access to information about its initiatives. Our goal is to keep this information timely and accurate. If errors are brought to our attention, we will try to correct them. However, the Commission accepts no responsibility or liability whatsoever with regard to the information on these fiches and WIKI.

[1] Synthesis research papers include either meta-analysis or systematic reviews with quantitative results. Details can be found in the methodology section of the WIKI.

[2] Eurostat. https://ec.europa.eu/eurostat/statistics-explained/index.php?title=Glossary:Crop_rotation.

[3] Monocropping is the continuous growing of the same species on a piece of land over a sequence of growing seasons (C.A. Francis, P. Porter, in Encyclopedia of Applied Plant Sciences (Second Edition), 2017..