View Source

<div class="banner_general_fiche"><div class="table-wrap"><table class="ficheTable" style="width: 99.1985%;"><colgroup><col style="width: 60%;"><col style="width: 20%;"></colgroup><tbody><tr><td class="confluenceTd"><h1 style="text-align: center;" title="" id="banner_title"></h1></td></tr></tbody></table></div></div>


<script>
var title = $('#title-text').find('a').text();
var mytitle = title.replace('_',' ');
$('#banner_title').text(mytitle + ' Fiche');

</script>

<style>
.banner_general_fiche { 
  height: 194px;  
  padding-right: 20px;
  background-color: #00afef;
 }
.banner_general_fiche h1 {
  position: relative;
  font-size: 1.7 !important;
  font-family: corbel;
  color: #ffffff !important;
  letter-spacing: -0.01em;
  font-weight: normal;
  line-height: 1.25;
  top: 64px;
  font-weight: bold;
  margin-left: 30px;
}
#banner_title {
   text-transform: uppercase; 
}
.table-wrap {
    overflow-x: hidden;
    overflow-y: hidden;
}
.banner_general_fiche td { 
    border: 0px !important;
	height: 170px;
	width: 100%;
}  
.content-wrapper {
  font-family: corbel;
  position: relative;
}
</style>

<style>
.highlight-green {
   color: #000000;
   background-color: #92d050 !important;
}
table.confluenceTable td.confluenceTd.highlight-green>p {
    background-color: #92d050 !important;
}
.highlight-red {
   color: #000000 !important;
   background-color: #ff0000 !important;
}
table.confluenceTable td.confluenceTd.highlight-red>p {
    background-color: #ff0000 !important;
}
.highlight-yellow {
   color: #000000;
   background-color: #ffc000 !important;
}
table.confluenceTable td.confluenceTd.highlight-yellow>p {
    background-color: #ffc000 !important;
}
.highlight-grey {
   color: #000000 !important;
   background-color: #a4a4a4 !important;
}
table.confluenceTable td.confluenceTd.highlight-grey>p {
    background-color: #a4a4a4 !important;
}

#Agroforestry_GENERAL-GENERALFICHE-AGROFORESTRY {
  color: #F8F8FF !important;

}
#main-content { font-family: corbel; }

.wiki-content img.confluence-embedded-image { cursor: default !important;}  

</style>

Data extracted in January 2022
Fiche created in February 2024

Note to the reader: This general fiche summarises all the environmental and climate impacts of COVER AND CATCH CROPS found in a review of 40 synthesis papers[1]. These papers were selected from an initial number of 158 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 4 to 269. Therefore, the assessment of impacts relies on a large number of results from the primary studies, obtained mainly in field conditions, or sometimes in lab experiments or from model simulations.

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 runoff 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:
- Crops sown on purpose during the fallow season, or undersown to winter/spring main crops, or sown between rows of tree or vineyard crops as mean of soil living cover.
- Spontaneous vegetation left growing with the objective of covering the soil.
- Mono- or multi-species cover/catch crops including legumes (N-fixing species), non-legumes (grass or broadleafs) or mixtures.
- Permanent/annual intercropping in orchards, i.e. refers to the maintenance of a permanent cover crop in the alleys, such as aromatics, while annual intercropping means the presence of cover crops in the alleys that are annually harvested or incorporated into the soil.
- Cover/catch crops are terminated before the main cash crop is harvested, by different strategies: Mechanical, tillage with direct incorporation to soil or herbicide termination.
- Cover/catch crops biomass, after termination, can be either:
left on soil as mulch or green manure.
incorporated as green manure.
harvested and exported from the field.
- 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.
- NA

2. EFFECTS OF THE FARMING PRACTICE ON CLIMATE AND ENVIRONMENTAL IMPACTS

(table 1)

The table below shows the number of synthesis papers 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. Details on the quality assessment of the synthesis papers can be found in the methodology section of this WIKI.

Out of the 40 selected synthesis papers, 32 included studies conducted in Europe, and 39 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.

				Statistically tested			Non-statistically tested
Impact	Metric	Intervention	Comparator	Significantly positive	Significantly negative	Non-significant	Non-statistically tested
Increase Biodiversity	biodiversity	Cover crops	Bare soil	1	0	0	0
Increase Carbon sequestration	SOC	Cover crops	Bare soil	9	0	4	1
		Legume cover crops	Bare soil	3	0	0	0
		Non-legume cover crops	Bare soil	2	0	0	0
Increase GHG emissions	CH4 emission	Cover crops	Bare soil	0	1	0	0
Increase GHG emissions	N2O emission	Cover crops	Bare soil	2	4	4	0
Decrease GHG emissions	N2O emission	Legume cover crops	Bare soil	0	2	0	0
Decrease GHG emissions	N2O emission	Non-legume cover crops	Bare soil	1	1	2	0
Decrease Nutrient leaching and run-off	N loss	Cover crops	Bare soil	6	0	2	0
		Legume cover crops	Bare soil	2	0	5	0
		Non-legume cover crops	Bare soil	7	0	0	0
Decrease Nutrient leaching and run-off	P loss	Cover crops	Bare soil	1	0	0	0
		Legume cover crops	Bare soil	1	0	0	0
		Non-legume cover crops	Bare soil	1	0	0	0
Decrease Pests and diseases	Natural enemies	Cover crops	Bare soil	0	0	1	0
Decrease Pests and diseases	Pests	Cover crops	Bare soil	2	0	2	0
Decrease Pests and diseases	Weeds	Cover crops	Bare soil	5	0	2	0
		Legume cover crops	Bare soil	1	0	0	0
		Non-legume cover crops	Bare soil	1	0	0	0
Increase Plant nutrient uptake	Nutrient use efficiency	Legume cover crops	Bare soil	1	0	0	0
Increase Plant nutrient uptake	Nutrient use efficiency	Non-legume cover crops	Bare soil	0	0	1	0
Increase Pollination	Pollination	Cover crops	Bare soil	0	0	0	1
Increase Soil biological quality	Soil biological quality	Cover crops	Bare soil	7	0	2	0
		Legume cover crops	Bare soil	1	0	0	0
		Non-legume cover crops	Bare soil	1	0	1	0
Decrease Soil erosion	Soil erosion	Cover crops	Bare soil	4	0	1	1
		Legume cover crops	Bare soil	1	0	0	0
		Non-legume cover crops	Bare soil	1	0	0	0
Increase Soil nutrients	Soil nutrients	Cover crops	Bare soil	4	0	4 (3)	0
		Legume cover crops	Bare soil	1	0	0	0
		Non-legume cover crops	Bare soil	1	0	0	0
Increase Soil physico-chemical quality	Soil physico-chemical quality	Cover crops	Bare soil	3	0	0	1
Increase Soil water retention	Soil water retention	Cover crops	Bare soil	2	3	3	1
		Legume cover crops	Bare soil	1	0	0	0
		Non-legume cover crops	Bare soil	0	0	1	0
Increase Water use	Water use efficiency	Cover crops	Bare soil	1	0	0	0
Increase Crop yield	Cash crop yield	Cover crops	Bare soil	5	1	8	1
		Legume cover crops	Bare soil	7	1	2	0
		Non-legume cover crops	Bare soil	0	3	7	0

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.

Impact	Factors
Carbon sequestration	Cash crop (Ref11), Climatic conditions (Ref16), Cover crop biomass production (Ref4), Cover crop residue management (Ref22), Cover crop type (Ref22), Crop residue retention (Ref16), Growing window (Ref4), No factor reported (Ref24), Pedo-climatic zone (Ref4), Rotation type (Ref4), Soil depth (Ref11, Ref16), Soil pH (Ref16), Soil texture (Ref4, Ref11), Tillage (Ref4) and Time scale (Ref16)
GHG emissions	Cover crop residue management (Ref22), Cover crop type (Ref22), N fertilisation rate (Ref33, Ref38), Period (Ref33) and Period of Nitrous Oxide Measurement (Ref38)
Nutrient leaching and run-off	Cover crop biomass production (Ref28), Cover crop species (Ref28), Mean annual precipitation (Ref3, Ref28), Mean annual temperature (Ref3), N cover crop input to soil (Ref40), No factor reported (Ref38), Planting dates (Ref28), Slope gradient (Ref3) and Soil texture (Ref28)
Pests and diseases	Cash crop seeding time (Ref23), Cover crop biomass production (Ref14, Ref23), Herbicides use (Ref23), No factor reported (Ref24), Seeding rate (Ref23), Sowing season (Ref23), Ternination period (Ref23), Tillage management (Ref23), Time after cover crop (Ref14) and Type of weed (Ref14)
Soil biological quality	Annual precipitation (Ref5), Climate (Ref12), Fertilizer rate (Ref12), No factor reported (Ref24), Soil P content (Ref19), Soil pH (Ref5), Soil texture (Ref5), Soil type (Ref12), Termination method (Ref5) and Termination type (Ref12)
Soil erosion	Slope gradient (Ref3) and Vegetation coverage (Ref3)
Soil nutrients	Cover crop residue management (Ref22), Cover crop type (Ref22) and Duration (Ref35)
Soil physico-chemical quality	Associated practices (Ref17), Soil depth (Ref30), Soil texture (Ref17) and Years of treatment (Ref17)
Soil water retention	Cover crop biomass production (Ref7), Pedo-climatic zone (Ref7), Soil depth (Ref30), Soil type (Ref7) and Termination method (Ref7)
Water use	Cover crop biomass production (Ref7), Pedo-climatic zone (Ref7), Soil type (Ref7) and Termination method (Ref7)
Crop yield	Cash crop seeding time (Ref7), Climate (Ref40), Climate zone (Ref2), Cover crop biomass production (Ref7), Cover crop phenology (Ref40), Fruit tree age (Ref2), Mineral fertilisation rate (Ref40), N fertilisation rate (Ref37), Nitrogen fertilisation rates (Ref34), No factor reported (Ref24), Pedo-climatic zone (Ref7), Soil P content (Ref19), Soil type (Ref7, Ref25, Ref37, Ref40), Termination of cover crop before main crop (Ref34), Termination type (Ref25) and Tillage (Ref40)

4. SYSTEMATIC REVIEW SEARCH STRATEGY

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

Parameter	Details
Keywords	WOS: TS= ("cover* crop" OR "catch crop" OR "winter cover" OR "soil cover") AND TS= ("meta-analy" OR "systematic* review" OR "evidence map" OR "global synthesis" OR "evidence synthesis" OR "research synthesis") and SCOPUS: 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")
Time reference	No time restriction.
Databases	Web of Science and Scopus: run on 01 January 2022
Exclusion criteria	The main criteria that led to the exclusion of a synthesis paper are: 1) The paper is not written in English., 2) The paper is neither a systematic review nor a meta-analysis of primary research., 3) Land use is not cropland., 4) The analysis is not based on pairwise comparisons, 5) The topic of the meta-analysis is out of the scope of this review., 6) The topic is not on a/more specific landscape features. and 7) The full text is not available. The search returned 108 synthesis papers from WOS and SCOPUS on Cover and catch crops plus other 50 retrieved in the search of other farming practices, potentially relevant for the practice object of our fiche. From the 158 potentially relevant synthesis papers, 27 were excluded after reading the title and abstract, and 29 after reading the full text according to the above-mentioned criteria. Finally, 40 synthesis papers were selected.

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.

Ref Num	Author(s)	Year	Title	Journal	DOI
Ref1	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
Ref2	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
Ref3	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
Ref4	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
Ref5	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
Ref6	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
Ref7	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
Ref8	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
Ref9	Chen J., Xiao H., Li Z., Liu C., Ning K., Tang C.	2020	How effective are soil and water conservation measures (SWCMs) in reducing soil and water losses in the red soil hilly region of China? A meta-analysis of field plot data	Science of The Total Environment 735, 139517	10.1016/j.scitotenv.2020.139517
Ref10	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
Ref11	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
Ref12	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
Ref13	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
Ref14	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
Ref15	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
Ref16	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
Ref17	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
Ref18	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
Ref19	Hallama, M; Pekrun, C; Lambers, H; Kandeler, E	2019	Hidden miners - the roles of cover crops and soil microorganisms in phosphorus cycling through agroecosystems		10.1007/s11104-018-3810-7
Ref20	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
Ref21	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
Ref22	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
Ref23	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
Ref24	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
Ref25	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
Ref26	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
Ref27	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
Ref28	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
Ref29	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
Ref30	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
Ref31	Basche, AD; DeLonge, MS	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
Ref32	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
Ref33	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
Ref34	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
Ref35	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
Ref36	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
Ref37	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
Ref38	Basche, AD; Miguez, FE; Kaspar, TC; Castellano, MJ;	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
Ref39	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
Ref40	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

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

[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] Inglett, P.W., Reddy, K.R., Corstanje, R., 2005. Encyclopedia of Soils in the Environment | ScienceDirect.