Soil properties affecting weed distribution in spring cereal and vegetable fields Raimo Erviö, Seppo Hyvärinen, Leila-Riitta Erviö and Jukka Salonen Erviö, R.', Hyvärinen, S. 1 , Erviö, L.-R. 2 & Salonen, J.2 1994. Soil properties affecting weed distribution in spring cereal and vegetable fields. Agricultural Science in Finland 3: 497-504. (Agricultural Research Centre of Finland, ' Insti- tute of Soils and Environment, and 2 Institute of Plant Protection, FIN-31600 Jokioi- nen, Finland.) The incidence of weed species in 482 cereal and 224 vegetable field plots in southern and central Finland was investigated. The occurrence of the 16 most common weed species was related to soil properties. Chenopodium album L., La- mium spp. L. and Fallopio convolvulus (L.) Love were more abundant in clay than in coarse mineral or organic soils. Elymus repens (L.) Gould, Erysimum cheiran- thoides L., Lapsana communis L., Myosolis arvensis (L.) Hill and Poa annua L. thrived better in coarse than in clay soils. Polygonum lapalhifolium L. and Rumex spp. L. were more abundant in organic than in mineral soils, and Lamium spp. was not found at all in organic soils. Rumex spp., Poa annua and Polygonum lapalhifolium had higher densities at the lowest pH level, < 5.2. Lamium spp. and Myosolis spp. thrived at the highest pH levels. Poa annua and Spergula arvensis were most common in soils where the extractable calcium concentration was below 1000 mg L 1 soil. Key words: Finnish fields, soil type, soil pH, soil organic matter content, soil extractable calcium Introduction A study was carried out in 1982 - 1984 to deter- mine the occurrence of weeds in Finnish spring cereals (Erviö and Salonen 1987) and vegetable fields. Of special interest was the importance of farming management and field factors on weed infestation. As part of this study, the present pa- per discusses the influence of soil types and soil properties on the occurrence of weed species in cereal and vegetable fields of southern and cen- tral Finland. Diverse conclusions have been drawn about the effect of soil factors on the incidence of weed species. The role of soil pH in the abundance of some species has been reported by some workers (Ferdinandsen 1918, de Vries 1934,Trautmann 1954). Low pH may be a restrictive factor in the success of many pretentious weed species, some of which are considered to be calciphiles. The importance of available nutrients for weed abundance has also been investigated. It would seem however, that physical soil proper- ties such as porosity, aeration, waterholding ca- pacity and humus content have a more marked effect on the abundance of weeds than do chemi- cal soil properties (Ellenberg 1951, Rehder 1959). 497 Agricultural Science in Finland 3 (1994) https://www.c-info.fi/en/info/?token=x3XZANs1IXzkF9m0.hIlTBl2MFrVR1pIH28VV7Q.V4LPcApAa7d7DoZRfIg39y_w3kPggawxrhVHOW_TQVHzyKRLKoczNxONCWJb4UdRzI8-87sC-fauj23jXabcwn0CY0ot9Ccm65xMK6o_Sw2FFE2uYGp4tl4ZdaJBcCUafWkqrpb1isHN8eoih3E8w6oioYGWDaEo5febqOGY5Rbib4zEH4H91dnBkKeJTCjq3spw8joW__Ha23Dv_x17wAAiVbWrFZi98mZ8jTADezYioGiJcjIwfDMzg3TccUuM7nmFmi4eso01aAPgV0lLbisvN5iinrx7x7JXgbnPWeJY_5om0_Am3aeK8VceIebUjUEKhqwd_nF0A1NZPnFVy8LBKcgGjbIx Table 1. Distribution of soil types in different localities. Number of plots in soil-type groups Cereal fields Vegetable fields Localities Coarse Clay Organic Coarse Clay Organic mineral soils soils mineral soils soils soils soils Archipelago 4 18 2 8 2 2 Southwestern Finland 100 200 23 20 7 74 Southern Finland 1 22 - 17 48 4 Eastern Finland 38 - 5 19 1 1 Western Finland 6 14 4 3 3 1 Central Finland 20 3 2 6 -3 Ostrobothnia 12 I 7 4 1 Total 181 258 43 77 62 85 Material and methods A weed survey was conducted in spring cereal and vegetable fields in ten localities in southern and central Finland in 1982-1984. A detailed de- scription of the localities and data on spring ce- reals were given in previous publications (Erviö and Salonen 1987, Salonen and Erviö 1988, Salonen 1993). In those papers the occurrence of weeds was analysed from 3-5 plots in every field but here weed numbers have been used only for the plots from which the soil samples were taken. The material has been divided into seven locality groups (Table 1). Weed data on vegeta- ble fields were gathered in the same localities as the spring cereal data. The spring cereals were wheat, oats and barley and the most common vegetable crops were carrot, onion, cabbage and swede. The number of weeds was counted from a total of 482 cereal plots in 265 fields and from 224 vegetable plots in 112 fields on 379 farms (Table 1). The weed assessment was made on 0.25 m 2 circular sample plots during the second half of July. The interdependences between weed densities and soil properties were studied. Only the 16 most common weed species were ana- lysed. Soil samples were taken from the plough layer (0-20 cm) by mixing five separate auger pricks together. They were dried and ground to pass through a 2-mm sieve. Soil pH(H 2 0), organic mat- ter content and extractable calcium, potassium, magnesium and phosphorus concentrations were measured on all soil samples. In addition, the particle-size analysis was made on 101 samples to confirm that the soil type was correct. Soil pH(H2 0) was determined on a soil:water V/V suspension of 1:2.5. The organic carbon con- tent of the soil was determined by the automated dry ashing method. The samples were combusted in an oxygen atmosphere and the C02 gas formed was measured with a solid-state infrared detec- tor. A conversion factor of 1.73 was used to con- vert organic carbon to organic matter (0.M.). Calcium and other macronutrients were extract- ed from the soil using a 0.5 N ammonium acetate 0.5 N acetic acid (AAAc) solution (pH 4.65), the extraction ratio being 1:10 V/V (Vuorinen and Mäkitie 1955). Concentrations of Ca, K, Mg and P were measured on the soil extracts employing an inductive coupled plasma emission spectro- meter (ICP). The concentrations are given as mil- ligrams per litre of soil. The occurrence of weeds was compared in the soil-type groups. The material was divided into three soil groups: coarse mineral, clay and organ- ic soils. The first group comprised sand, fine- 498 Agricultural Science in Finland 3 (1994) sand, silt and glacial till soils, and the last one peat, mould and gyttja soils. A soil sample was classified as peat if the O.M. content was at least 40%, as mould if the O.M. content was 20 - 40% and as gyttja if O.M. was at least 6% in lake sediment soil. The soil types were distributed un- equally between localities. Thus, in some locali- ties of southern Finland there were no organic soil plots and in eastern Finland no clay soil plots (Table I). Differences in the occurrence of weeds in the various soil type groups were analysed with Tukey’s HSD multiple range test (P = 0.05). The statistically significant differences in the tables are based on the analysis with log-transformed data. The results given in the tables are back- transformed from the logarithmic mean values. Data transformation was used to achieve normal distribution and homogeneity of variances. Results and discussion Soil type The analysis of weed densities (plants nr2 ) indi- cated differences in the occurrence of weed spe- cies in the various soil types better than did the analysis of weed biomass. It apparently takes only a single big weed plant to raise the biomass rang- es to an unreasonably high level. In a previous paper (Salonen 1993) examining the total weed density, not the density by species, differences were found between soil types in the total weed biomass but not in the total weed density. Here, divergent densities of weed species were found in different soil-type groups (Table 2). How- ever, the densities of some weeds differed in the soils of cereal and vegetable fields, indicating the strong influence of crop type on weed inci- dence (cf. Andreasen et al. 1991). The abun- dance of weeds varied from one species to anoth- er. Chenopodium album had the highest density of all species, averaging 74 plants nr2 in the clay soils of vegetable fields. The densities of seven weed species averaged only 1 plant nr2 or less. Chenopodium album and Lamium spp. in both cereal and vegetable fields and Fallopio convol- vulus in cereal fields were more dense in clay soils than in coarse mineral or organic soils. Sim- ilar results have been reported for Lamium (Reh- der 1959,Andreasen et al. 1991), and Fallopia convolvulus (Granström 1962). In contrast, Korsmo (1925) reported that Chenopodium al- bum and Lamium purpureum occured in equal densities in all kinds of soil, and Render (1959) considered Fallopia convolvulus an indifferent species. Weed species that thrivedbetter in coarse min- eral than clay soils were Elymus repens, Lapsana communis, Myosotis arvensis and Poa annua and, in addition, Erysimum cheiranthoides and Sper- gula arvensis in cereal fields. Andreasen and Streibig (1990) and Andreasen et al. ( 1991 ) like- wise found a negative correlation between clay content and the density of Elymus repens, Myo- sotis arvensis and Spergula arvensis. Korsmo (1925) and, later, Render (1959) and Granström (1962) showed that Spergula arvensis was par- ticularly prevalent in light soil types. Elymus re- pens, Myosotis arvensis and Spergula arvensis were characterized for mineral soil species by Raatikainen and Raatikainen (1983); this was not found in the present data. Chenopodium album and Galium spp. were more abundant in mineral than in organic soils, especially in vegetable fields. Lapsana commu- nis and Viola arvensis occurred more abundantly in coarse mineral than in organic soils, and Lamium spp. was not found at all in organic soils. In the whole material, Polygonum lapathifolium was more common in organic than in mineral soils as was Rumex spp. in cereal fields. Gran- ström (1962) and Raatikainen and Raatikai- nen (1983) also reported a greater abundance of P. lapathifolium in organic than in mineral soils, and Streibig et al. (1984) found a positive corre- lation between soil organic matter and Rumex ac- etosella. Mukula et al. (1969) found 30 plants nr2 of P. lapathifolium in organic soils but only 6 and 12 plants nr2 in clay and coarse mineral soils, respectively. In this study the density of Spergula arvensis was higher in organic soils than in clay soils. 499 Agricultural Science in Finland 3 (1994) Table 2. Weed density in different soil types. Arithmetic means and geometric means, with superscripts denoting statistically significant (P < 0.05) differences. Plants nr2 Cereal fields Vegetable fields Coarse Clay Organic Coarse Clay Org. mineral soils soils mineral soils soils soils soils Chenopodium album L. 1 18 26 8 56 74 14 2.3"2 6.2* 2.1b 8.4* 4.8* 1.6b Elymus repens (L.) Gould 18 2 8 23 7 6 1.6* 0.5 b 1.2» 2.5» 0.8b 0.7 b Erysium cheiranthoides L. 16 4 9 9 3 2 I.l* 0.7 b 0.9*b 1.7* 1.0*b 0.9b Fallopio convolvulus (L.) Love 3 7 2 4 13 0.9 b 1.7* 0.8 b 0.6 b 0.5 b 1.5» Galeopsis spp, L. 8 17 25 5 4 12 2.0b 3.6“ 3.4* l.0b 0.9b 2.0* Galium spp. L. 3 8 0 6 3 < 1 0.5b 0.8» 0.6»b 0.8» 0.7» 0.4b Lamium spp, L. 3 8 0 2 6 0 0.6 b o.B* 0.4 b 0.5 b 0.9» 0.4» Lapsana communis L. 16 4 9 14 <1 <1 1.7» 0.9 b 0.5 b 1.2» 0.4 b 0.5 b Myosotis arvensis (L.) Hill 8 2 1 2 <1 <1 1.2» 0.6 b 0.6b 0.6* 0.5* b 0.4 b Poa annua L. 5 1 1 29 I 9 0.6* 0.4 b 0.5*b 1.7* 0.4b I.l* Polygonum lapathifoliumL. 1 1 9 2 17 0.5 b 0.5 b 0.9* 0.5 b 0.5b 1.4* Rumex spp, L. 1 <1 7 6.4 n = 79 n = 100 n = 137 n=l6l n=lls n=ll4 Weed Chenopodium album 22.758.512.6“' 4.6b 0.50.7 0.4b 0.5b 4.84.8 o.5c o.ö 1* 0.41.1 0.4b 0.5 b 20.56.8 1.2“ 0.8“b 9.02.8 1.2“ 0.7b 5.40.4 0.7“ 0.4b 6.23.2 1.2* 0.9“b 25.1 18.8 26.3 30.4 4.6b4,2 b 4.0b 5.1b Lamium spp. 2.3 4.2 6.7 10.1 0.9“b0.6ab 0.7*b 0.7“b Lapsana communis 5.3 10.5 9.4 8.7 1.0“b l.lab 1.2“ 1.0“b Myosotis arvensis 5.0 4.1 4.3 1.8 0.7“b 0.8“ 1.0“ 0.7“ Poa annua 6.2 0.4 3.7 5.4 0.6b 0.4' 0.5b 0.6b Polygonum lapathifolium 9.0 1.4 0.8 0.8 1.5 0.6b 0.5b 0.5b 0.5 b Rumex spp. 0.2 0.2 0.1 0.1 0.4b 0.4b 0.4b 0.4 b Spergula arvensis 16.6 2.6 2.4 3.2 1.0“ 0.7“b 0.6b 0.6b 1 Densities marked with different superscripts differ from each other significantly (P < 0.05) between pH classes. Their density was highest at pH values below 5.2, being nearly ten times as high as at pH val- ues at least 5.2. Rumex acetosella has also been mentioned as an indicator of soil acidity (Nielsen 1926, Ellenberg 1950, Render 1959 and Streibig et al. 1984). This opinion is not held by all authors, however (Kivinen 1931 and Åslander 1941). Another species abundant in acid soil was Polygonum lapathifolium, as also mentioned by Ferdinandsen (1918) and Render (1959); El- lenberg (1950) in contrast considered it a pH- indifferent species. The density ofPoa annua was noticeably more abundant at pH < 5.2 than at > 5.5. Spergula arvensis weeds were numer- ous at pH 5.5 - 5.7 but significantly less so at pH >6.1. Species thriving at high pH levels were La- mium spp., Lapsana communis and Myosotis spp. Lamium species grew most abundantly at pH > 6.4. Nielsen (1926), Ellenberg (1950), Render (1959) and Andreasen et al. (1991) also reported Lamium spp. thriving at high soil pH levels. The density of Myosotis spp. was higher at PH > 5.8 class than at PH <5.5. However, there was no clear indication of its demand for high pH. Ellenberg (1950) mentioned Myosotis arvensis as an indifferent species. Extractable nutrients There was no distinct, consistent relationship be- tween extractable potassium and phosphorus and weed density. Soil-extractable calcium seemed to affect the densities of some weed species (Table 4). Elymus repens, Poa annua, Rumex spp. and Spergula arvensis grew at their highest density 501 Agricultural Science in Finland 3 (1994) Table 4. Weed density in different extractable calcium classes in cereal and vegetable fields. Arithme- tic means, and geometric means, with superscripts denoting statistically significant (P < 0.05) differ- ences. Weed Plants m : Extractable Ca concentration mg I -1 soil < 1000 1000-1499 1500-1999 2000-2499 >2500 n = 73 n = 162 n = 181 n=ll2 n=l7B Elymus repens 18.410.5 8.79.8 6.1 1.5“' l.l ab 0.9ab 0.9 ab 0.8 b Myosotis arvensis 1.21.2 0.60.5 0.2 0.8 ab I.o* 0,7 ab 0.7ab 0.5 b Lapsana communis 13.813.6 5.93.3 3.9 1.2a 1.4a 0.8 1» 0.8 bc 0.6 C Poa annua 28,9 1.15.3 5.52.0 1.3 a 0.5 b 0.6b 0.6b 0.5 b Spergula arvensis 28.74.3 4.91.1 1.9 1.4a 1.0ac 0.8bc 0.6b 0.7 bc Stellaria media 15.827.1 23.031.6 24.5 2.0 b 3.9 ab 3.2* 2.8a 3.1 a 1 Densities marked with different superscripts differ from each other significantly (P < 0,05) between Ca classes. in the lowest Ca class (< 1000 mg I' 1 soil). The abundance of Poa annua differed most clearly. Negative significances of the dependence (F val- ue) of weed density on the concentration of ex- tractable calcium of soil were found only in Ely- mus repens, Lapsana communis and Myosotis ar- vensis (Table 5). According to de Vries (1934), however, Spergula arvensis did not indicate a low calcium concentration of soil as it grew well in soil rich in calcium, too. Stellaria media was the only species to occur in a significantly higher density in the highest Ca classes (over 1500 mg) than in the class below 1000 mg Ca. In conclusion, the occurrence of several weed species differed between soil types. Crop type influenced the incidence of all weeds, and soil pH and the extractable calcium concentration the incidence of some. The density of Poa annua, Polygonum lapathifolium and Rumex spp. was highest in the lowest pH class but that of Lamium spp. in the highest one. The occurrence of some species, e.g. Poa annua and Spergula arvensis, can apparently be reduced with liming as they had a very high density in the lowest extractable calcium class. Table 5. Statistical significance of dependence (F value, ANOVA), of soil pH and concentration of extractable cal- cium ofsoil on weed density. + = ascending, - = descend- ing. F values Extractable calcium Soil pH Weed Chenopodium album 15.3***+ 10.2**+ Elymus repens - B.l**- Lamium spp. 18.7***+ Lapsana communis 15.1***+ 21.0***- Myosotis arvensis 14.5***+ Poa annua 17 g***_ Polygonum lapathifolium 28.2***- Rumex spp. 21.4***-Rumex spp. 21.4***- Stellaria media s,4**+ 6.6**+ ** = P