Type of organic fertilizer rather than organic amendment per se increases abundance of soil biota

Abstract

Addition of organic amendments is a commonly used practice to offset potential loss of soil organic matter from agricultural soils. The aim of the present study was to examine how long-term addition of organic matter affects the abundance of different soil biota across trophic levels and the role that the quality of the organic amendments plays. Here we used a 17-year-old fertilization experiment to investigate soil biota responses to four different organic fertilizers, compared with two mineral nitrogen fertilizers and no fertilization, where the organic fertilizers had similar carbon content but varied in their carbon to nitrogen ratios. We collected soil samples and measured a wide range of organisms belonging to different functional groups and trophic levels of the soil food web. Long-term addition of organic and mineral fertilizers had beneficial effects on the abundances of most soil organisms compared with unfertilized soil, but the responses differed between soil biota. The organic fertilizers generally enhanced bacteria and earthworms. Fungi and nematodes responded positively to certain mineral and organic fertilizers, indicating that multiple factors influenced by the fertilization may affect these heterogeneous groups. Springtails and mites were less affected by fertilization than the other groups, as they were present at relatively high abundances even in the unfertilized treatment. However, soil pH had a great influence on springtail abundance. In summary, the specific fertilizer was more important in determining the numerical and compositional responses of soil biota than whether it was mineral or organic. Overall, biennial organic amendments emerge as insufficient, by themselves, to promote soil organisms in the long run, and would need to be added annually or combined with other practices affecting soil quality, such as no or reduced tillage and other crop rotations, to have a beneficial effect.

Ant Community Is Not Influenced by the Addition of Olive Mill Pomace Compost in Two Different Olive Crop Managements

“…Such cultural practices seem to be determinant in drastically reducing ant activity in spring in the traditional grove (in soil and canopy), whereas in the superintensive grove, the ant presence in spring was much greater, it was reduced in summer, when fewer food sources can be found in the canopy but resumed some activity at the end of summer/beginning of autumn. On the contrary, the addition of compost did not produce a significant effect on the ant assemblage, although other arthropods increased its presence, such as Acari, Arachnida, Coleoptera, and other invertebrates (study under evaluation), which agrees with other authors [10][11][12][13].…”

“…The addition of compost (or other by-products of agriculture, such as manure and sewage) has significant effects on the crop because it incorporates different nutrients and carbon in the soil and can influence the soil's inhabitants. This latter aspect is the subject of different studies [9][10][11][12][13] with extensive reviews, which in general highlight the beneficial effect on the soil fauna, with an increase in arthropods such as Acari (order Oribatida as the most mentioned, but also Mesostigmata and Prostigmata), Collembola, some families of Coleoptera (Carabidae it is one of the most cited), and other inhabitants such as Nematoda or Lumbricidae (earthworms), but depending on the type of by-product used and the specific conditions (crop, management) of the study.…”

Intake and fixation of organic carbon in grain agrophytocenosis of Western Siberia

“…Despite the fact that in the variant with NPK for 4.0 t/ha of grain, the total carbon loss was 2.7 t/ha per year, due to the higher biomass of by-products in this variant, 14% of the incoming carbon with plant residues was fixed in the soil. The introduction of increasing doses of mineral fertilizers activates the soil microflora and enhances the mineralization process [25]. This leads to an increase in organic carbon losses in the variants with NPK for 5.0 and 6.0 t/ha of grain to 4.1 and 4.0 t/ha, which corresponds to losses of 114 and 110% of the total carbon intake into the soil for the year.…”

Conservation Tillage in Medicinal Plant Cultivation in China: What, Why, and How

“…These suggest that soil tillage practices influence P. pruinosa nesting choice, and production practices should be considered to protect pollinators. In a 17 year fertilization experiment, biennial organic amendments were insufficient for promoting soil organisms in the long run [155] and should be combined with NT or RT to attain a beneficial effect on soil quality.…”