Soil Sciences
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- ItemEffects of improved pigeonpea fallows on biological and physical soil properties and their relationship with maize yield(Springer Nature, 2021) Musokwa, Misheck; Mafongoya, Paramu L.Declining soil properties have triggered lower maize yields among smallholder famers in South Africa. Legume trees such as pigeonpea can be used as improved fallows to replenish degraded soils. The objectives of the study were to: (1) examine the effects of improved pigeonpea fallows on enhancing biological, physical soil properties and maize yield responses and (2), analyze the relationship of maize grain yield to biological and physical soil properties after improved pigeonpea fallows at Wartburg, South Africa. Pigeonpea fallows were established in 2015/16 season and terminated in 2017 and subsequently maize was planted. A randomized complete block design replicated three times was used with five treatments: continuous sole maize without fertilizer (T1), natural fallow then maize (T2), pigeonpea + grass—pigeonpea then maize (T3), maize + pigeonpea—pigeonpea then maize (T4), two-year pigeonpea fallow then maize (T5). Improved pigeonpea fallows increased maize yields through improvement in soil macrofauna species abundance, richness and diversity, aggregate stability, infiltration rate. Pigeonpea fallows increased maize yield by 3.2 times than continuous maize without fertilizer. The maize grain yield (3787 kg ha−1), was the highest on two-year pigeonpea fallows while continuous maize without fertilizer had the least (993 kg ha−1). There was a significant positive correlation between soil macrofauna indices and physical soil properties to maize yields. Smallholders who have limited access to fertilizers can sustainably use improved fallows to restore degraded soils to achieve higher maize yields in South Africa.
- ItemComparison of bacterial communities in roots of selected trees with and without summer truffle (Tuber aestivum) ectomycorrhiza(Sciendo (De Gruyter), 2021-06-08) Siebyła, Marta; Szyp-Borowska, IwonaIn this study, we examined the effect of the presence of mycorrhiza and ascomata of summer truffle (Tuber aestivum) on the bacterial composition of roots from small trees growing in selected sites of the Nida Basin. Qualitative DNA sequencing methods such as Sanger and next-generation sequencing (NGS) were used. The Sanger method revealed different bacterial species compositions between the samples where summer truf fle ascomata was recorded and control samples. Five genera of bacteria could be distinguished: Bacillus, Erwinia, Pseudomonas, Rahnella and Serratia, among which the most numerous were Pseudomonas (Gammmaproteobacteria class) at 32.9%. The results obtained by the NGS method also showed differences in species composition of the bacteria depending on the study sample. Seven genera of bacteria were distinguished: Rhizorhabdus, Methylotenera, Sphingomonas, Nitrosospira, Streptomyces, Methyloceanibacter and Niastella, which dominated in roots from the truffle sites. Telmatobacter, Roseiarcus, Granulicella, Paludibaculum, Acidipila, Acidisphaera and Aliidongia dominated in roots from the control sites. With the NGS method, it is possible to identify the microbiome of a whole root, while only a root fragment can be analysed by the Sanger method. These results extend the scope of knowledge on the preferences of certain groups of bacteria associated with truffles and their influence on the formation of ascomata in summer truffles. Our results may also be useful in selecting and monitoring sites that promote ascomata of Tuber aestivum.
- ItemLiming alkaline clay soils: effects on soil structure, nutrients, barley growth and yield(Taylor & Francis Group - Informa UK Limited, 2022-07-04) Gunnarsson, Anita; Blomquist, Jens; Persson, Lars; Olsson, Åsa; Hamnér, Karin; Berglund, KerstinLiming before cultivation of sugar beets is favourable even on alkaline soils but knowledge of response in other crops is lacking. Therefore, effects of ground limestone (GL) and structure lime (SL1 slaked lime or SL2 mix of ground limestone and slaked lime) were evaluated in southern Sweden on soil structure, growth and nutrient concentration in barley under four fertilisation strategies 1.5–2 years after application. All lime products increased aggregate stability, but with variations between locations. A lower proportion of large aggregates was found in both limed treatments, and a higher proportion of small aggregates in SL. In barley, grain yield was unaffected while shoot numbers and biomass in first node stage increased for GL and biomass increased further for SL. Structure lime increased potassium concentration in plants in first node stage, due to more potassium in the product. Both lime types increased molybdenum concentration. Ground limestone reduced zinc concentration compared with no liming. Finer seedbed tilth and increased aggregate stability may explain increased biomass for GL. Higher potassium content in SL might be a further explanation. No interactions between liming and fertilisation were found. In conclusion, on the soil types studied, no change of fertilisation strategy is needed due to liming.
- ItemMitigating phosphorus leaching from a clay loam through structure liming(Taylor & Francis Group - Informa UK Limited, 2022-11-01) Norberg, Lisbet; Aronsson, HelenaPhosphorus (P) losses from clay soils can be mitigated by introducing measures for improving soil structure. These include structure liming, where a mixture of CaO or Ca(OH)2 and CaCO3 is added to the soil. In a field experiment with separately tile-drained plots on a clay loam in Sweden, we examined the effects of structure liming on leaching of total-P, phosphate P (PO4-P) and total nitrogen (N) during three years after initial application. The treatments included two application rates (8 and 16 t ha−1) of a common product in comparison with a control (no lime). Effects of structure liming emerged during the second and third year after application, with 45 and 38% lower total-P leaching than in the unlimed control. A significant effect of the application rate was found in the third year. Nitrogen leaching and crop yield were not affected. As expected, soil pH raised following structure lime addition. Measurements of aggregate stability did not confirm the reduction in P leaching, indicating that it is important to measure P concentrations in drainage water directly when assessing the effect of structure liming.
- ItemExploring structural sediment connectivity via surface runoff in agricultural lands of Finland(Taylor & Francis Group - Informa UK Limited, 2022-10-26) Tähtikarhu, M; Räsänen, T; Oksanen, J; Uusi-Kämppä, J.Spatial information on the distribution of erosion areas and sediment transport pathways within agricultural landscapes is limited. Thus, we assess structural sediment connectivity via surface runoff by using a digital elevation model (2 × 2 m2) and RUSLE-based erosion estimates to compute index of connectivity (IC) and sediment delivery estimates. The variables were analyzed within and between two topographically contrasting subcatchments. We found greater spatial variability of IC within a subcatchment than between the subcatchments. The majority of field parcel areas (65%–97%) were structurally connected to adjacent open ditches and streams. Areas with high erosion estimates also tended to be structurally well-connected, both at the pixel (Pearson r = 0.58–0.63) and parcel scale (r = 0.49–0.67). The IC model was not highly sensitive to parameter variations. In contrast, the magnitude of sediment delivery estimates was highly sensitive to parameter variations. However, based on the high rank correlation (Spearman rs > 0.95) between computed sediment delivery estimates, the tool provided consistent information on potentially high sediment delivery areas. More empirical data and dynamic model applications could be applied to improve the accuracy of the estimates. The method provides a feasible tool to generate open data on connectivity.