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Data extracted in February 2022
Note to the reader: This general fiche summarises all the environmental and climate impacts of cover and catch crops, found in a review of 39 synthesis research papers [1]. These papers were selected from an initial number of 159 obtained through a systematic literature search strategy, according to the inclusion criteria reported in section 4.
As each synthesis research paper involves a number of primary research papers ranging from 4 to 269 (often around 50), the assessment of impacts relies on a large number of results obtained mainly from real farms and field experiments (carried out by scientists in situations close to real farming environment).
1. DESCRIPTION OF THE FARMING PRACTICE
Description | Cover crops are grown to provide vegetative cover between rows of main crops in orchards and vineyards, or in the period between two main arable crops to prevent erosion and minimize the risk of surface run-off by improving the infiltration. They may also function as catch crops, which scavenge the remaining nitrogen after the main crop is harvested, thereby reducing nutrient losses from leaching. They are temporary crops that may be cut and removed or incorporated into the soil. The practice of incorporating crops into the soil to provide nutrient is defined as "green manuring".[2] Spontaneous vegetation left growing with the same purpose of cover crops is also included under this practice. |
Key descriptors | Cover/catch crops include:
Cover/catch crops are terminated before the main cash crop is harvested, by different strategies:
Cover/catch crops biomass, after termination, can be either:
Catch/cover crops or spontaneous living soil cover are compared to bare soil during fallow season (e.g. winter) or to uncovered soil/active removal of spontaneous vegetation by tillage. |
2. DESCRIPTION OF THE IMPACTS OF THE FARMING PRACTICE ON ENVIRONMENT AND CLIMATE
The table below shows the number of synthesis papers reporting positive, no-effect or negative, based on the statistical comparison of the intervention and the control. In addition, we include the number of synthesis papers reporting relevant results, but without statistical test of the effects (here labelled as 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 methodology section of this WIKI.
Out of the 39 synthesis papers selected, 33 reported studies conducted in Europe and 38 have a quality score higher than 50%. Some synthesis papers reported more than one impact.
Impact | Metric | Intervention | Positive | Negative | No effect | Uncertain results |
Increase carbon sequestration | Soil organic carbon | Cover crops **** | 9 (9) | 0 (0) | 4 (4) | 1 (1) |
|
| Legume cover crops | 3 (3) | 0 (0) | 0 (0) | 0 (0) |
|
| Non-legume cover crops | 2 (2) | 0 (0) | 0 (0) | 0 (0) |
Increase soil nutrients |
| Cover crops | 4 (4) | 0 (0) | 4 (3) | 0 (0) |
|
| Legume cover crops | 2 (2) | 0 (0) | 0 (0) | 0 (0) |
|
| Non-legume cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
Increase soil water retention |
| Cover crops | 4(4) | 3 (3) | 3 (3) | 1 (1) |
|
| Legume cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
|
| Non-legume cover crops | 0 (0) | 0 (0) | 1 (1) | 0 (0) |
Decrease nutrient leaching and run-off |
| Cover crops | 6 (6) | 0 (0) | 2 (2) | 0 (0) |
|
| Legume cover crops | 2 (2) | 0 (0) | 5 (5) | 0 (0) |
|
| Non-legume cover crops | 7 (7) | 0 (0) | 0 (0) | 0 (0) |
Decrease soil erosion |
| Cover crops | 4 (4) | 0 (0) | 1 (1) | 1 (1) |
|
| Legume cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
|
| Non-legume cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
Improve soil biological quality |
| Cover crops | 7 (7) | 0 (0) | 1 (1) | 0 (0) |
|
| Legume cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
|
| Non-legume cover crops | 1 (1) | 0 (0) | 1 (1) | 0 (0) |
Improve soil physico-chemical quality |
| Cover crops | 2 (2) | 0 (0) | 0 (0) | 0 (0) |
Decrease pests and diseases | Increase natural enemies of pests | Cover crops | 0 (0) | 0 (0) | 1 (1) | 0 (0) |
| Decrease pests *** | Cover crops | 2 (2) | 0 (0) | 2 (2) | 0 (0) |
| Decrease weeds | Cover crops | 5 (5) | 0 (0) | 2 (2) | 0 (0) |
|
| Legume cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
|
| Non-legume cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
Decrease GHG emissions ** | CH4 | Cover crops | 0 (0) | 1 (1) | 0 (0) | 0 (0) |
| N2O | Cover crops | 2 (2) | 3 (3) | 4 (4) | 0 (0) |
|
| Legume cover crops | 0 (0) | 2 (2) | 0 (0) | 0 (0) |
|
| Non-legume cover crops | 2 (2) | 0 (0) | 1 (1) | 0 (0) |
Increase biodiversity |
| Cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
Increase pollination |
| Cover crops | 0 (0) | 0 (0) | 0 (0) | 1 (1) |
Increase plant nutrient uptake | Nitrogen utilisation efficiency | Legume cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
|
| Non-legume cover crops | 0 (0) | 0 (0) | 1 (1) | 0 (0) |
Improve water use | Increase plant water use efficiency | Cover crops | 1 (1) | 0 (0) | 0 (0) | 0 (0) |
Increase crop yield * |
| Cover crops | 5 (5) | 1 (1) | 8 (8) | 1 (1) |
|
| Legume cover crops | 7 (7) | 1 (1) | 3 (3) | 0 (0) |
|
| Non-legume cover crops | 0 (0) | 3 (3) | 7 (7) | 0 (0) |
* yield and quality parameters of the main cash crop subsequent to cover crops; ** data refer only to direct emissions from soil during the fallow period; ***other than weeds; ****including all types of cover crops, natural vegetation cover and mixed-species cover crops.
3. DESCRIPTION OF THE KEY FACTORS INFLUENCING THE SIZE OF THE EFFECT
Only the factors explicitly studied in the reviewed synthesis papers are reported below. Details regarding the factors can be found in the summary of the meta-analyses.
IMPACTS | FACTORS |
Carbon sequestration | Growing window (ref 6 ),Cover crop biomass production (ref 6 ),Rotation type (ref 6 ),Tillage (ref 6 ),Soil texture (ref 6 12 ),Pedo-climatic zone (ref 6 ),Cash crop (ref 12 ),Soil depth (ref 12 22 ),Cover crop type (ref 16 ),Cover crop residue management (ref 16 ),No factor reported (ref 17 ),Climatic conditions (ref 22 ),Soil pH (ref 22 ),Time scale (ref 22 ),Crop residue retention (ref 22 ) |
GHG emissions | Cover crop type (ref 16 ),Cover crop residue management (ref 16 ),N fertilisation rate (ref 28 34 ),Period (ref 28 ),Period of Nitrous Oxide Measurement (ref 34 ) |
Soil nutrients | Cover crop type (ref 16 ),Cover crop residue management (ref 16 ) |
Nutrients loss | Mean annual precipitation (ref 2 24 ),Slope gradient (ref 2 ),Mean annual temperature (ref 2 ),Soil texture (ref 24 ),Cover crop species (ref 24 ),Planting dates (ref 24 ),Cover crop biomass production (ref 24 ),No factor reported (ref 34 ) |
Pest and disease control | Time after cover crop (ref 10 ),Type of weed (ref 10 ),Cover crop biomass production (ref 10 20 ),No factor reported (ref 17 ),Sowing season (ref 20 ),Seeding rate (ref 20 ),Ternination period (ref 20 ),Cash crop seeding time (ref 20 ),Tillage management (ref 20 ),Herbicides use (ref 20 ) |
Soil erosion | Vegetation coverage (ref 2 ),Slope gradient (ref 2 ) |
Soil biological quality | Termination method (ref 4 ),Soil texture (ref 4 ),Soil pH (ref 4 ),Annual precipitation (ref 4 ),Climate (ref 9 ),Termination type (ref 9 ),Fertilizer rate (ref 9 ),Soil type (ref 9 ),No factor reported (ref 17 ),Soil P content (ref 21 ) |
Soil physico-chemical quality |
|
Water retention | Pedo-climatic zone (ref 3 ),Soil type (ref 3 ),Termination method (ref 3 ),Cover crop biomass production (ref 3 ),Years of treatment (ref 18 ),Soil texture (ref 18 ),Associated practices (ref 18 ) |
Plant water use efficiency | Pedo-climatic zone (ref 3 ),Soil type (ref 3 ),Termination method (ref 3 ),Cover crop biomass production (ref 3 ) |
Crop yield | Climate zone (ref 1 ),Fruit tree age (ref 1 ),Pedo-climatic zone (ref 3 ),Soil type (ref 3 33 ),Cover crop biomass production (ref 3 ),Cash crop seeding time (ref 3 ),No factor reported (ref 17 ),Soil P content (ref 21 ),Nitrogen fertilisation rates (ref 27 ),Termination of cover crop before main crop (ref 27 ),N fertilisation rate (ref 33 ) |
Food quality | Climate zone (ref 1 1 ),Fruit tree age (ref 1 1 ),Climatic zone (ref 1 ) |
4. SYSTEMATIC REVIEW SEARCH STRATEGY
Keywords | TOPIC: ("cover* crop*" OR "catch* crop*" OR "winter cover*" OR "soil cover*”) AND TOPIC: ("meta-analy*" OR "systematic* review*" OR "evidence map" OR "global synthesis" OR "evidence synthesis" OR "research synthesis") or TITLE-ABS-KEY ("cover* crop*" OR "catch* crop*" OR "winter cover*" OR "soil cover*”) AND TITLE-ABS-KEY ("meta-analy*" OR "systematic* review*" OR "evidence map" OR "global synthesis" OR "evidence synthesis" OR "research synthesis") |
Search dates | No time restrictions |
Databases | Web of Science and Scopus, run in January 2022. |
Selection criteria | Five main criteria led to the exclusion of a synthesis paper: (1) the paper does not deal with cover/catch crops; (2) the paper does not assess the impacts of cover/catch crops in comparison to bare soil, including pairwise comparison derived from the same field trials; (3) the paper reported results regarding only fertilization using green manure, without dealing with the overall effect of the cover/catch crop; (4) cover crops are studied as factors on pairwise comparison between different farming practices; (5) the paper is neither a meta-analysis nor a systematic review including quantitative results. Synthesis papers that passed the relevance criteria were subject to critical appraisal carried out on paper-by-paper basis. Due to the high number of synthesis papers available, in case that more than 10 were available for one single impact, we selected the 10 most recent ones including data in the EU. From the 158 potentially relevant synthesis papers,61 were excluded after reading the title and abstract, and 56 after reading the full text according to the above-mentioned criteria. Finally,39 synthesis papers were selected for cover/catch crops. |
5. LIST OF SYNTHESIS PAPERS INCLUDED IN THE REVIEW OF THE FARMING PRACTICE IMPACTS
Number | Author | Year | Title | Reference | doi |
1 | Fang, LF; Shi, XJ; Zhang, Y; Yang, YH; Zhang, XL; Wang, XZ; Zhang, YT | 2021 | The effects of ground cover management on fruit yield and quality: a meta-analysis | ARCHIVES OF AGRONOMY AND SOIL SCIENCE | 10.1080/03650340.2021.1937607 |
2 | Liu, R; Thomas, B; Shi, XJ; Zhang, XL; Wang, ZC; Zhang, YT | 2021 | Effects of ground cover management on improving water and soil conservation in tree crop systems: A meta-analysis | CATENA 199, 105085 | 10.1016/j.catena.2020.105085 |
3 | Wang, J; Zhang, SH; Sainju, UM; Ghimire, R; Zhao, FZ | 2021 | A meta-analysis on cover crop impact on soil water storage, succeeding crop yield, and water-use efficiency | Agricultural Water Management, 256, 107085 | 10.1016/j.agwat.2021.107085 |
4 | Muhammad, I; Wang, J; Sainju, UM; Zhang, SH; Zhao, FZ; Khan, A | 2021 | Cover cropping enhances soil microbial biomass and affects microbial community structure: A meta-analysis | Geoderma 381, 114696 | 10.1016/j.geoderma.2020.114696 |
5 | Puissant, J; Villenave, C; Chauvin, C; Plassard, C; Blanchart, E; Trap, J | 2021 | Quantification of the global impact of agricultural practices on soil nematodes: A meta-analysis | SOIL BIOLOGY & BIOCHEMISTRY, 161, 108383 | 10.1016/j.soilbio.2021.108383 |
6 | McClelland, SC; Paustian, K; Schipanski, ME | 2021 | Management of cover crops in temperate climates influences soil organic carbon stocks: a meta-analysis | Ecological applications, 31, 3, e02278 | 10.1002/eap.2278 |
7 | Crystal-Ornelas, R; Thapa, R; Tully, KL | 2021 | Soil organic carbon is affected by organic amendments, conservation tillage, and cover cropping in organic farming systems: A meta-analysis | Agriculture, Ecosystems & Environment 312, 107356 | 10.1016/j.agee.2021.107356 |
8 | Jian, Jinshi; Lester, Brandon J.; Du, Xuan; Reiter, Mark S.; Stewart, Ryan D. | 2020 | A calculator to quantify cover crop effects on soil health and productivity | Soil and Tillage Research 199, 104575 | 10.1016/j.still.2020.104575 |
9 | Kim, N; Zabaloy, MC; Guan, KY; Villamil, MB | 2020 | Do cover crops benefit soil microbiome? A meta-analysis of current research | SOIL BIOLOGY & BIOCHEMISTRY, 142, 107701. | 10.1016/j.soilbio.2019.107701 |
10 | Nicholas, V; Martinez-Feria, R; Weisberger, D; Carlson, S; Basso, B; Basche, A | 2020 | Cover crops and weed suppression in the US Midwest: A meta-analysis and modeling study | AGR ENV LETT 2020;5, e20022 | 10.1002/ael2.20022 |
11 | Payen FT, Sykes A, Aitkenhead M, Alexander P, Moran D, MacLeod M. | 2020 | Soil organic carbon sequestration rates in vineyard agroecosystems under different soil management practices: A meta-analysis | J. Clean. Prod. Elsevier 125736 | 10.1016/j.jclepro.2020.125736 |
12 | Jian, Jinshi; Du, Xuan; Reiter, Mark S.; Stewart, Ryan D. | 2020 | A meta-analysis of global cropland soil carbon changes due to cover cropping | Soil Biol. Biochem. 143, 107735 | 10.1016/j.soilbio.2020.107735 |
13 | Morugan-Coronado, A; Linares, C; Gomez-Lopez, MD; Faz, A; Zornoza, R | 2020 | The impact of intercropping, tillage and fertilizer type on soil and crop yield in fruit orchards under Mediterranean conditions: A meta-analysis of field studies | Agric. Syst. 178, 102736 | 10.1016/j.agsy.2019.102736 |
14 | Bai, XL; Zhang, ZB; Cui, JJ; Liu, ZJ; Chen, ZJ; Zhou, JB | 2020 | Strategies to mitigate nitrate leaching in vegetable production in China: a meta-analysis | Environmental Science and Pollution Research 27, 18382–18391 | 10.1007/s11356-020-08322-1 |
15 | Lee, H; Lautenbach, S; Nieto, APG; Bondeau, A; Cramer, W; Geijzendorffer, IR | 2019 | The impact of conservation farming practices on Mediterranean agro-ecosystem services provisioning-a meta-analysis | REG ENVIRON CHANGE | 10.1007/s10113-018-1447-y |
16 | Gu, JX; Nie, HH; Guo, HJ; Xu, HH; Gunnathorn, T | 2019 | Nitrous oxide emissions from fruit orchards: A review | Atmospheric Environment 201, 166-172 | 10.1016/j.atmosenv.2018.12.046 |
17 | Muhammad, I., Sainju, U.M., Zhao, F., (…), Fu, X., Wang, J. | 2019 | Regulation of soil CO2 and N2O emissions by cover crops: A meta-analysis | Soil and Tillage Research 192, pp. 103-112 | 10.1016/j.still.2019.04.020 |
18 | Shackelford, GE; Kelsey, R; Dicks, LV | 2019 | Effects of cover crops on multiple ecosystem services: Ten meta-analyses of data from arable farmland in California and the Mediterranean | LAND USE POLICY, 88, 104204. | 10.1016/j.landusepol.2019.104204 |
19 | Basche, AD; DeLonge, MS | 2019 | Comparing infiltration rates in soils managed with conventional and alternative farming methods: A meta-analysis | PloS one, 14 (9): e0215702. | 10.1371/journal.pone.0215702 |
20 | Meyer, N; Bergez, JE; Constantin, J; Justes, E | 2019 | Cover crops reduce water drainage in temperate climates: A meta-analysis | Agronomy for Sustainable Development 39, 3 | 10.1007/s13593-018-0546-y |
21 | Osipitan OA, Dille JA, Assefa Y, Radicetti E, Ayeni A, Knezevic SZ | 2019 | Impact of cover crop management on level of weed suppression: A meta-analysis | Crop Science 59, 3, 833-842 | 10.2135/cropsci2018.09.0589 |
22 | Hallama, M; Pekrun, C; Lambers, H; Kandeler, E | 2019 | Hidden miners - the roles of cover crops and soil microorganisms in phosphorus cycling through agroecosystems | NA | 10.1007/s11104-018-3810-7 |
23 | Bai, XX; Huang, YW; Ren, W; Coyne, M; Jacinthe, PA; Tao, B; Hui, DF; Yang, J; Matocha, C | 2019 | Responses of soil carbon sequestration to climate-smart agriculture practices: A meta-analysis | Global Change Biology, 25, 2591-2606 | 10.1111/gcb.14658 |
24 | Toler, HD; Auge, RM; Benelli, V; Allen, FL; Ashworth, AJ | 2019 | Global Meta-Analysis of Cotton Yield and Weed Suppression from Cover Crops | Crop science 59, 3, 1248-1261 | 10.2135/cropsci2018.10.0603 |
25 | Winter, S; Bauer, T; Strauss, P; Kratschmer, S; Paredes, D; Popescu, D; Landa, B; Guzman, G; Gomez, JA; Guernion, M; Zaller, JG; Batary, P | 2018 | Effects of vegetation management intensity on biodiversity and ecosystem services in vineyards: A meta-analysis | J APPL ECOL | 10.1111/1365-2664.13124 |
26 | Thapa R, Mirsky SB, Tully KL | 2018 | Cover Crops Reduce Nitrate Leaching in Agroecosystems:A Global Meta-Analysis | Journal of Environmental Quality 47, 6, 1400-1411 | 10.2134/jeq2018.03.0107 |
27 | Osipitan, OA; Dille, JA; Assefa, Y; Knezevic, SZ | 2018 | Cover Crop for Early Season Weed Suppression in Crops: Systematic Review and Meta-Analysis | Agronomy Journal 110, 6, 2211-2221 | 10.2134/agronj2017.12.0752 |
28 | Mahal, NK; Castellano, MJ; Miguez, FE | 2018 | Conservation Agriculture Practices Increase Potentially Mineralizable Nitrogen: A Meta-Analysis | SOIL SCI SOC AM J, 82, 1270–1278 | 10.2136/sssaj2017.07.0245 |
29 | Marcillo GS, Miguez FE | 2017 | Corn yield response to winter cover crops: An updated meta-analysis | JOURNAL OF SOIL AND WATER CONSERVATION 72, 3, 226 -239 | 10.2489/jswc.72.3.226 |
30 | Han, Z; Walter, MT; Drinkwater, LE | 2017 | N2O emissions from grain cropping systems: a meta-analysis of the impacts of fertilizer-based and ecologically-based nutrient management strategies | NUTRIENT CYCLING IN AGROECOSYSTEMS, 107, 335-355. | 10.1007/s10705-017-9836-z |
31 | Bowles, TM; Jackson, LE; Loeher, M; Cavagnaro, TR | 2017 | Ecological intensification and arbuscular mycorrhizas: a meta-analysis of tillage and cover crop effects | Journal of applied ecology 54, 6, 1785-1793 | 10.1111/1365-2664.12815 |
32 | Basche, A; DeLonge, M | 2017 | The Impact of Continuous Living Cover on Soil Hydrologic Properties: A Meta-Analysis | SOIL SCI SOC AM J, 81, 5, 1179-1190 | 10.2136/sssaj2017.03.0077 |
33 | Alvarez, Roberto; Steinbach, Haydee S.; De Paepe, Josefina L. | 2017 | Cover crop effects on soils and subsequent crops in the pampas: A meta-analysis | Soil and Tillage Research 170, 53-65 | 10.1016/j.still.2017.03.005 |
34 | Wortman, Sam E. | 2016 | Weedy fallow as an alternative strategy for reducing nitrogen loss from annual cropping systems | Agronomy for Sustainable Development 61 | 10.1007/s13593-016-0397-3 |
35 | Pecio A., Jarosz Z. | 2016 | Long-term effects of soil management practices on selected indicators of chemical soil quality [Wpływ wieloletniego stosowania zabiegów agrotechnicznych na wybrane właściwości chemiczne gleb] | Acta Agrobotanica 69, 2 | 10.5586/aa.1662 |
36 | Valkama E, Lemola R, Känkänen H, Turtola E | 2015 | Meta-analysis of the effects of undersown catch crops on nitrogen leaching loss and grain yields in the Nordic countries | Agriculture, Ecosystems & Environment 203, 93-101 | 10.1016/j.agee.2015.01.023 |
37 | Basche, A.D.; Miguez, F.E.; Kaspar, T.C.; Castellano, M.J.; | 2014 | Do cover crops increase or decrease nitrous oxide emissions? A meta-analysis | JOURNAL OF SOIL AND WATER CONSERVATION, 69, 471-482. | 10.2489/jswc.69.6.471 |
38 | Quemada, M.; Baranski, M.; Nobel-de Lange, M. N. J.; Vallejo, A.; Cooper, J. M. | 2013 | Meta-analysis of strategies to control nitrate leaching in irrigated agricultural systems and their effects on crop yield | AGRICULTURE ECOSYSTEMS & ENVIRONMENT | 10.1016/j.agee.2013.04.018 |
39 | Tonitto, C; David, MB; Drinkwater, LE | 2006 | Replacing bare fallows with cover crops in fertilizer-intensive cropping systems: A meta-analysis of crop yield and N dynamics | AGRICULTURE ECOSYSTEMS & ENVIRONMENT, 112, 58–72. | 10.1016/j.agee.2005.07.003 |
[1] Synthesis research papers include either meta-analysis or systematic reviews with quantitative results.
[2] Inglett, P.W., Reddy, K.R., Corstanje, R., 2005. Encyclopedia of Soils in the Environment | ScienceDirect.