Improvement of an elutriation method for estimation of weed seedbank in the soil

Abstract

A model experiment was conducted to compare hand extraction (elutriation) under running water and elutriation using the device Analysette 3, the two methods for estimation of weed seedbank in the soil. Technical parameters have been assessed for efficient operating of the device. We studied the time required for elutriation of soil samples and the time for collecting, counting and identifying the separated seeds. No significant difference in the effect of the used elutriation method on results of qualitative and quantitative estimation of weed seedbank densities has been found at any of the three locations differing in soil texture (silty loam, loam and clay loam soil). The time necessary for elutriation of soil samples was highly significantly shorter if the device was used, by 35.5 to 42.9% depending on soil texture vs. hand elutriation. The shortest time was assessed for silty loam soil. By contrast, the time needed for selecting, counting and identifying seeds was shortest for clay loam soil. This time was 46 and 92% longer for loam and silty loam soil, respectively. These differences were statistically highly significant. Comparing the seedbank in the soil, a significantly lower number of weed seeds as well as species was found on silty loam soil vs. the two locations with heavier soils. Amaranthus retroflexus was a dominating species at all locations, and on silty loam soil also Chenopodium album. Of a total number of 32 weed species detected in our experiment, 28 were annual and only four perennial (Cirsium arvense, Elytrigia repens, Rumex obtusifolius and Sonchus arvensis).Keywords: weed seedbank in soil; methods for assessment; elutriation methods; labour consumptionThe weed seedbank in the soil is caused by living reproduction organs of weeds. These are seeds and fruits (thereinafter seeds), shoots and root buds of vegetative organs present in the soil or on its surface.To assess a number of seeds in the topsoil is rather labour-and time-consuming process (Thompson and Grime 1979, Rahman et al. 1995). Some questions concerning particularly soil sampling (a number of samples, sample size for an analysis, a sampling technique use of various types of core samplers, sampling depth, etc.) have not been defined yet. According to Gross (1990), results can be influenced by the sampling time, a method for estimation and identification of seeds. Findings presented in literature have been obtained by sampling and an analysis of partial samples (Dvoøák and Krejèíø 1974), and based on the analysis of an average sample (Deèkov 1975).There are two methods for enumeration of weed seeds in the soil: a separation method when seeds are collected from the soil sample and counted, and a vegetation method when the seeds are left in sampled soil to germinate. Then, individual species are identified based on morphological characteristics of weed seedlings.The separation methods include elutriation (extraction by washing) and flotation methods. A common aim of these methods is to separate seeds from soil using physica...

Soil seedbank: Old methods for new challenges in agroecology?

“…Because sample washing is time‐consuming, different machines have been built to automate the sieving (Fay & Olson, 1978; Kovach et al, 1988; Pannacci et al, 2015; Smutný & Křen, 2002; Thorsen & Crabtree, 1977; Wiles et al, 1996). For all machines, the samples were placed in a closed mesh container through which water under pressure could be pumped.…”

“…For all machines, the samples were placed in a closed mesh container through which water under pressure could be pumped. Such machines are much faster than manual sieving (Pannacci et al, 2015; Smutný & Křen, 2002) and it is possible to process a larger amount of soil (Kovach et al, 1988) or several samples at the same time (Wiles et al, 1996).…”

Ecology of soil seed banks: Implications for conservation and restoration of natural vegetation: A review

“…The second method is vegetation method, when the seeds are left in sampled soil to germinate. Then, individual species are identified based on morphological characteristics of species (Smutny and Kren, 2002). Extraction methods are labor intensive; but are better suited to quantifying changes in seed banks, which require repeated sampling over time.…”

The Impact of Under-Vine Management on the Weed Seedbank in the Soil

“…Hoeing was carried out at the same time as chemical treatment. The modified methodology by Dvořák and Krejčíř (1973), adjusted by Smutný and Křen (2002), was used for the evaluation of the weed seedbank in the soil samples. Soil samples were taken on 16 th October 2013 and 9 th October 2014 from 6 places below the grapevine (2 untreated places, 2 mechanically controlled places, 2 chemically controlled places).…”