Earthworm distributions are not driven by measurable soil properties. Do they really indicate soil quality?

Abundance and distribution of earthworms in agricultural fields is frequently proposed as a measure of soil quality assuming that observed patterns of abundance are in response to improved or degraded environmental conditions. However, it is not clear that earthworm abundances can be directly related to their edaphic environment, as noted in Darwin’s final publication, perhaps limiting or restricting their value as indicators of ecological quality in any given field. We present results from a spatially explicit intensive survey of pastures within United Kingdom farms, looking for the main drivers of earthworm density at a range of scales. When describing spatial variability of both total and ecotype-specific earthworm abundance within any given field, the best predictor was earthworm abundance itself within 20–30 m of the sampling point; there were no consistent environmental correlates with earthworm numbers, suggesting that biological factors (e.g. colonisation rate, competition, predation, parasitism) drive or at least significantly modify earthworm distributions at this spatial level. However, at the national scale, earthworm abundance is well predicted by soil nitrate levels, density, temperature and moisture content, albeit not in a simple linear fashion. This suggests that although land can be managed at the farm scale to promote earthworm abundance and the resulting soil processes that deliver ecosystem services, within a field, earthworm distributions will remain patchy. The use of earthworms as soil quality indicators must therefore be carried out with care, ensuring that sufficient samples are taken within field to take account of variability in earthworm populations that is unrelated to soil chemical and physical properties.

HUBUNGAN POPULASI CACING TANAH TERHADAP C-ORGANIK DAN N-TOTAL DI LAHAN BUDIDAYA HORTIKULTURA DAN MONOKLUTUR TANAMAN KOPI DI DESA NDUARIA KECAMATAN KELIMUTU

This study aims to determine the relationship between Earthworm Population and C-organic and N-total in Horticulture and Coffee Monoculture cultivation in Nduaria Village, Kelimutu District. This research was conducted using an exploratory method that is carried out by direct observation from the observation location. How to calculate earthworms using the hand sorting method. The method commonly used for the determination of C-organic is the Walkley and Black method, while the method used for the determination of N-total is the Kjehdahl method. This method is used because it is considered simple, fast, easy to do, and requires little equipment. The results of this study indicate that in horticultural land there is no earthworm population found at all depths. Earthworm populations were found at all depths in the coffee plantation monoculture, the highest population was at a depth of 0-10 cm as many as 41 m2, Biomass was 9 g, and Biomass vs Population 0.21 m2. In horticultural fields, the highest c-organic and n-total is at a depth of 0-10 cm, the c-organic value is 3.03% (high criteria) and n-total is 0.47% (medium criteria). The close relationship between the earthworm population, biomass, and biomass versus population was positively correlated with c-organic and n-total in horticultural land and coffee monoculture.

Earthworm Populations In Agricultural Green Roofs And Their Influence On Soil Nitrogen, Greater Toronto Area

Earthworm consumption and egestion of organic materials can increase bioavailable nitrogen in soils. Along with other benefits resulting from their burrowing activities, this process can increase soil fertility. This research investigated whether earthworms were present, and whether a relationship between earthworms and increased ammonium and nitrate levels was seen in the soils of the agricultural green roofs sampled in the greater Toronto area. Earthworms were found at several of the agricultural green roofs, but low soil moisture, low organic carbon, shallow depth, and compactness may have inhibited the establishment of earthworm populations in some soils. Results showed a statistically significant increase in levels of ammonium, but not in nitrate, with the increasing presence of earthworms. Findings indicate that some degree of increased bioavailable nitrogen benefits, resulting from earthworm presence, that are evident in conventional agricultural soils, can also be possible in agricultural green roofs, with attention to management of soil conditions that support earthworm populations.

Earthworm Populations In Agricultural Green Roofs And Their Influence On Soil Nitrogen, Greater Toronto Area

Earthworm consumption and egestion of organic materials can increase bioavailable nitrogen in soils. Along with other benefits resulting from their burrowing activities, this process can increase soil fertility. This research investigated whether earthworms were present, and whether a relationship between earthworms and increased ammonium and nitrate levels was seen in the soils of the agricultural green roofs sampled in the greater Toronto area. Earthworms were found at several of the agricultural green roofs, but low soil moisture, low organic carbon, shallow depth, and compactness may have inhibited the establishment of earthworm populations in some soils. Results showed a statistically significant increase in levels of ammonium, but not in nitrate, with the increasing presence of earthworms. Findings indicate that some degree of increased bioavailable nitrogen benefits, resulting from earthworm presence, that are evident in conventional agricultural soils, can also be possible in agricultural green roofs, with attention to management of soil conditions that support earthworm populations.

Earthworm species in Musa spp. plantations in Brazil and worldwide

Bananas and plantains are major commodity/food crops that represent an important habitat for earthworms, although so far, no review is available on earthworm communities associated with banana/plantain crops worldwide. The Vale do Ribeira region is among the largest banana producing areas in Brazil, but little is known of the earthworms living there. Hence, the present study assessed earthworm populations and species in three banana plantations and adjacent Atlantic forest fragments along the Ribeira de Iguape River using standard (hand sorting) methodologies. Furthermore, we review earthworm populations reported in banana/plantain plantations worldwide. Only two species (Pontoscolex corethrurus, Amynthas gracilis) belonging to two families (Rhinodrilidae, Megascolecidae) were found in the Ribeira River valley, occurring concurrently. Abundance was low (< 13 indiv. m-2) compared with other banana plantations worldwide, that frequently surpassed 100 indiv. m-2. More than 70 studies reported earthworms from >200 banana plantations in 28 countries, and mean species richness was 2.7 per site, ranging from 1 to 10 species. Exotics predominated in most sites and P. corethrurus was the most prevalent species encountered. Overall, more than 104 species from 10 families were reported, with around 61 native and 43 exotic widespread species, mainly of the Megascolecidae, Lumbricidae and Acanthodrilidae families. Richness was highest in India (27 spp.) and the Canary Islands (25 spp.), but native species dominated only in a few countries and sites, while exotics were prevalent especially in island countries and Brazil. Lower-input practices appear to be important for earthworm communities and banana plantations can have large earthworm populations in some cases, which may be contributing to soil processes and plant production, topics that deserve further attention. However, many important banana-producing countries have not yet been evaluated, so further work is warranted, both in terms of applied ecology and biodiversity.

Three-Year Investigation of Tillage Management on the Soil Physical Environment, Earthworm Populations and Crop Yields in Croatia

The aim of this study was to determine the environmental suitability of conservation tillage systems. A 3-year experiment was conducted in Croatia, to study the effects of different tillage treatments on soil properties, with the following: deep (DC), shallow tine cultivation (SC) and ploughing (P). Soil penetration resistance (SPR) was significantly greater in P compared to DC in all three years. In 2016, it was found at 30–40 and 40–50 cm; in 2017 at 10–20 cm; in 2018 at 0–10 and 10–20 cm. However, SC was significantly greater at 20–30, 30–40 and 40–50 cm compared to P and DC in 2017. The greater surface coverage in DC and SC (>30%) as compared to P (<1%) provided significantly higher soil moisture content (SMC) in maize (2016) and soybean (2018). In 2017, SMC in SC was significantly lower than in P and DC. Regarding all the 3 years, the agronomic structure in DC and SC had significantly greater crumb ratio compared to P, whereas P had significantly higher dust ratio than DC and SC. Throughout the 15 measurements, DC provided the most favorable soil habitat (11 occasions out of 15). In 2017, the earthworm abundance was significantly higher in DC compared to SC. In all the three years, DC resulted the highest yield, however the difference was not significant. Higher surface coverage and SMC positively impacted the ratio of agronomic structure (decreased dust and increased crumb ratio) and earthworm abundance. It can be concluded that DC and SC provided greater soil coverage which positively affected SPR, SMC, agronomic structure and earthworm abundance as compared to P.