Experiences with intercropping design – 
a survey about pulse cereal-combinations in Europe
von Fragstein und Niemsdorff, P., Trydeman Knudsen, M. , Gooding, M.J., Dibet, A. & Monti, M.
Key words: Intercropping, cereal grain legume combinations, survey, European countries, EU project
Abstract
A survey was carried out within five European countries with regard to the practice of cereal grain legume intercropping. The mostly given combination was spring barley-spring pea beside 27 other combinations between pulses and cereals. 72 % of all examples consisted of spring varieties, the rest of winter varieties, mainly a special case of the French South West with mild winter climate. Intercrops were mainly used for feeding purposes. Best experiences were named as better yield stability, effective weed suppression, and good quality of feed. Of the negative experiences complicated mechanical weed regulation, unequal maturation and additional costs for separation were mostly named. The interviewed farmers showed predominantly positive prospects for the development of intercropping on their farms, problems with sowing techniques were only of minor importance.
Introduction
Intercropping per se corresponds to a very high extent to the concept of increased biodiversity within organic crop husbandry. It is mostly realised in multi-species mixtures of perennual pastures, partly in green manuring or undersowing approaches, much less in cultivation of main crops (Gliessman 2000). The latter aspects was focus of one workpackage of a European project <Intercropping of cereals and grain legumes for increased production, weed control, improved product quality and prevention of N-losses in European organic farming systems (QLK5-CT-2002-02352)> in order to record the daily practice, the experiences and the prospects of that cropping design within the farming community of organic farmers in Denmark, France, Italy, United Kingdom, and Germany.
Materials and methods
The survey was carried out in each country of the project partners by personal farm visits. A common questionnaire consisted mainly of questions concerning  intercropping, farm structure and personal estimations, experiences and demands. All data of 65 interviews were collected through an online php-based input mask, stored in a mysql database and finally statistically evaluated by SPSS.
Results
The use of intercropping design in the organic farms was mainly initiated from 1981 on (table 1), approximately 90 % of all counts could be referred to that period. Between 1981 and 1990 it was mainly implemented on German farms, followed by French and Danish farms. Ten years later most of the Danish (and French) farmers integrated intercropping into crop husbandry. After 2000 another 11 % followed into the same direction (DK > FR > UK). That also reflects the different periods of conversion. Among the German group there was a longer experience of organic farming practice compared to the colleagues of the other countries. 

Table 1: Since when intercropping was used? (% of all counts)
Year 	(N) 	(%) 	DE 	UK 	FR 	IT 	DK	
– 1970 	2 	3.1 	3.1 					
1971 – 1980 	5 	7.7 	3.1 		3.1 		1.5 	
1981 – 1990 	19 	29.2 	15.4 	 	9.2 		4.6 	
1991 – 2000 	32 	49.2 	7.7 	1.5 	13.8 	7.7 	18.5 	
> 2000 	7 	10.8 		1.5 	3.1 		6.2 	
Counts [N] 	65 	 	19.0 	2.0 	19.0 	5.0 	20.0 	

As reasons for intercropping six criteriae were named out of which intercrops for the production of feed was most prominent, especially in DE, DK and FR (table 2). Production for the market was the second criterium although the marketing due to necessary separation can only be realized with additional efforts and costs (table 5). Soil conservation was specified as third reason for working with intercropping, but on a distinctly lower level. The other criteria can be assessed as negligible with regard to  number and relevance for the daily practice. 
Table 2: Reasons for the use of intercrops (% of all counts)
Year 	(N) 	(%) 	DE 	UK 	FR 	IT 	DK	
Feed 	39 	60.0	23.1	1.5	16.9		18.5	
Market 	18 	27.7 			12.3 	4.6	10.8 	
Soil conservation 	5 	7.7 	4.6 	 		3.1		
Demonstration 	1 	1.5 	 			 	1.5 	
Research 	1 	1.5 		1.5 				
Seed production 	1 	1.5 	1.5					
Counts [N] 	65 	 	19.0 	2.0 	19.0 	5.0 	20.0 	

Table 3: Number of components per mixture (% per country)	Table 4: Frequency of spring and winter types (% per country)	

		
Although intercropping in most cases and countries relied on 2 component mixtures (table 3), 3- and more component mixtures were also appointed, mainly in DE, DK and FR. Most of the specified examples for intercrops were build up with spring pea (22 %), spring barley (22 %), oats (13 %), winter pea (9 %) and winter triticale (9 %). Of 28 different combinations for used intercrops three examples covered >50 % of all combinations: (A) spring barley-spring pea (24 %), (B) spring barley-spring oats-spring pea (15 %) and (C) winter pea-winter triticale (15 %). The latter example is a special situation of the mild winter climate in the South West of France. Example (A) was grown on 513 ha, example (C) on 200 ha. (table 4). There was a clear distinction between the mixtures of Danish farmers on the one hand (prevalence of pulses), and French and German farmers on the other hand (prevalence of cereals). 
Farmers were asked about positve and negative experiences and estimations of intercrops (table 5). Of the 13 arguments emphasizing the benefit of mixed cropping systems yield stability, effective weed suppression, good quality of feed, easier harvest, good precrop effect, and less pests and diseases covered > 60 % of all answers. The opposite perspective was seen with regard to more complicated mechanical weed control (15 %), unequal maturation (11 %), problems due to lodging and additional costs for separation (7 %). 
Table 5: Advantages and disadvantages of intercropping?
Positive	
(%)	
Negative	
(%)	

Yield stability	
15	
Mechanical weeding more complicated	
15	

Effective weed suppression	
12	
Unequal maturation	
11	

Good feed	
11	
Problems due to lodging	
7	

Easier harvest	
9	
Additional costs for separation	
7	

Good precrop effect	
9	
IC mixture at harvest unpredictable	
6	

Less pests & diseases	
7	
Marketing of mixed seeds	
4	

Less lodging risk for peas	
4	
Problems to preserve	
4	

Less labour	
2	
Grain losses at harvest	
4	

Better use of resources	
2	
Undersowing difficult in IC	
2	

More flexibility in rotational management	
2	

Higher yield	
2	

Higher diversity	
2	

Compensation	
2	

	

Table 6: Prospects of intercropping?
Entries	
(%)	

Maintain area	
27	

Expand area	
13	

IC with lupins	
11	

Change mixture	
11	

Change sowing technique	
6	

Reduce area	
5	

	
Among the group of interviewed farmers at least 40 % of the answers indicated maintenance and expansion of the area of intercropping in the next future of crop husbandry (table 6). Changes of the composition of mixtures were named as other aspects of wanted improvements of the intercrops. Aspects i.e. change of sowing technique or reduction of growing area were appointed less common. 
Discussion
The results of the survey reflect the findings of Rauber & Hof (2003) to a high extent. The positive experiences about better weed suppression are in accordance with findings of Hauggard et al. (2006), Jensen (2006) and Trenbath (1993). Technical problems such as adequate mechanical tools for sowing and weeding were not so much emphasized by the farmers as done by interviewed advisors within the study of Rauber & Hof (2003), but belonged to the mentioned obstacles towards the use of intercropping. There is a distinct tendency for simple combinations, most of the appointed examples consisted of 2 or 3 components. Thus the claim for increased biodiversity by cultivation of intercropped pulses and cereals is of limited value and should be supported by further genom intercrops i.e. mixtures of cultivars within the species (Finckh 2001). The longest experiences were found on organic farms in Denmark, France and Germany, whereas very limited numbers of farmers with intercrop experiences could be found in United Kingdom and Italy. Therefore most of the conclusions are related to the Danish, French and German data.
Conclusions 
Intercropping provides distinct benefits for organic farming systems. That is also true for the combination of pulses and cereals. It is desirable that scientific work is more concerned with related questions in order to convince advisors of these systems and to encourage practitioners to implement more of such cropping designs into their cultivation plans. 
Acknowledgments
This work was financed out of funds of the EU 5th framework.
References 
Finckh, M.R. (2001): Biodiversität in der Pflanzenzucht aus der Sicht der Phytopathologie und der Ökologischen Landwirtschaft. In: „Nutzung genetischer Ressourcen – ökologischer Wert der Biodiversität“, K. Hammer & T. Gladis (Hrsg.), ZADI, Bonn, S. 155-170.
Gliessman, S.R. (2000): Agroecology – ecological processes in sustainable agriculture. Lewis Publishers, Boca Raton. 
Hauggaard-Nielsen, H.; Andersen, M.; Jornsgaard, B. & Jensen, E. (2006): Density and relative frequency effects on competitive interactions and resource use in pea-barley intercrops. 
Field Crops Research 95: 256-267.
Trenbath, B. R. (1993): Intercropping for the management of pests and diseases. 
Field Crops Research 34: 381-405.
Rauber, R.& Hof, C. (2003): Fertigen einer Broschüre zum Anbau von Gemengen für die Praxis des Ökologischen Pflanzenbaus. Schlussbericht Geschäftsstelle Bundesprogramm Ökologischer Landbau, Bundesanstalt für Landwirtschaft und Ernährung (BLE), Bonn. 87 S. http://www.orgprints.org/4746, (accessed: 2005-02-03)
Jensen, E.S. (ed.) (2006): Intercropping of cereals and grain legumes for increased production, weed control, improved product quality and prevention of N-losses in European organic farming systems. Final Report of EU project (QLK5-CT-2002-02352), 383 p. http://www.intercrop.dk (accessed: 2006-12-02)