Woody species distribution across a savanna-dry forest soil gradient in the Brazilian Cerrado

Although richness and distribution of woody species in the Cerrado physiognomies have been extensively studied, the shifts of woody species from savanna physiognomies to dry forests have not yet been addressed. Here, we investigate the effect of soil physical-chemical traits on the woody species turnover between adjacent cerrado stricto sensu and dry forest physiognomies. Woody species were surveyed, and soil and topographic variables measured, in 30 10×40 m plots systematically distributed, with 15 plots in each physiognomy. We found a spatially structured distribution of woody species, and differences of soil traits between cerrado stricto sensu and dry forest areas, mainly related to the aluminum saturation, base saturation, and available phosphorus. Aluminum saturation increased toward the savanna area, while base saturation increased toward the dry forest. Most woody species predominated in one physiognomy, such as Callisthene major in the cerrado stricto sensu and Anadenanthera colubrina in the dry forest. Only 20% of the species were widely distributed across both physiognomies or, not often, restricted to the intermediary values of the soil gradient. General results indicate that contrasting soil traits between cerrado stricto sensu and dry forest produce a strongly spatially organized and sharp transition in terms of species distribution between these physiognomies.

Influence of Soil Genesis Factors on Gurghiu Mountain Forest Soils’ Physical and Chemical Properties

This research aimed to determine the values of chemical properties and the relationships between the main pedoecological factors that characterize the soils in the Gurghiu Mountains. The mapping surveys were carried out on an area of 4,647.36 ha located in the mixed mountain forest sites (FM2) (1,000–1,400 m altitude). The area was stratified into homogeneous site units in terms of climate, hydricity, and trophicity. At the level of the elementary site units, 35 main soil profiles and 46 control profiles were placed. The number of profiles was determined statistically to ensure an error of no more than 10%. Soil samples collected from the main profiles were analyzed in the laboratory. Soil’s properties values decreased on the soil’s profile (humus content from 15 to 2%, nitrogen from 1.1 to 0.5%, sum of exchangeable hydrogen from 20 to 9 me/100 g soil, and total cationic exchange capacity from 38 to 20 me/100 g soil), except the pH and the base saturation degree (the pH increased on profile from 4.5 to 6, and the base saturation degree from 40 to 70%). The soil properties, except for moisture, were significantly affected by altitude, and decreased when the altitude increased. Soil trophicity can be characterized by a soil index, the values of which were between 17 and 42 for the analyzed soils. These values indicated soil-specific trophicity levels from oligotrophic to eutrophic.

Soil Fertility Changes With Climate and Island Age in Galápagos: New Baseline Data for Sustainable Agricultural Management

While the extended absence of human influence has led to matchless natural conditions on the Galápagos archipelago, agricultural activities on the inhabited islands are increasingly affecting soil health and functioning. However, a systematic assessment of the agricultural soils on the Galápagos Islands is still absent. Plate tectonics and hotspot volcanism cause an eastward drift of the archipelago and result in a west-to-east soil age gradient from approx. 1 to 1,000 ka. In addition, precipitation regimes change from arid to humid with elevation on the higher-standing islands. The objective of this study was to investigate differences in soil fertility parameters and Mehlich (III)-extractable nutrient levels along these gradients in order to provide baseline information for sustainable agricultural management. Topsoil samples (0–20 cm) from 125 farms of the islands Isabela, Santa Cruz and San Cristóbal were analyzed. Gravel and sand content, pH, electrical conductivity, cation exchange capacity, base saturation, soil organic C and total N content tended to decrease with increasing island age, while clay content, soil macroaggregate stability, plant-available water and bulk density increased. Mehlich (III)-extractable base cations Ca, K, Mg and Na as well as P, Fe and Zn showed a decreasing tendency from the youngest to the oldest island, while Mn increased with island age. Mehlich (III)-extractable Cu and Na reached their highest levels on the most intensively farmed, intermediate-aged island Santa Cruz, likely related to anthropogenic inputs and irrigation with brackish water, respectively. Changes along the altitudinal climate gradient within the studied islands were most significant for soil pH, base saturation, and Mehlich (III)-extractable Ca and Mn. Our results highlight the importance of site-specific agricultural management to account for the strong heterogeneity in soil parameters among and within the Galápagos archipelago. The data provided herein shall serve as a baseline for targeted future management strategies to avoid soil degradation, restore and maintain soil functioning and, hence, sustain the soils’ provision of ecosystem services in this unique archipelago.

Peculiarities of acid-base properties of peat formed in various agroclimatic zones of the Altai mountainous region

The results of the study of acid-base indicators of peat in the Altai mountainous region are presented. The natural factors that in the aggregate determine the peculiarities of the physico-chemical properties of mountain peat of different agro-climatic zones of the Altai Mountains have been revealed. The variation in the acid values, total absorbed bases, adsorption capacity and the degree of saturation of raised-bog, transitional, fen peat, the number of exchangeable ions Ca2+ and Mg2+ has been estimated. The interrelation among these indicators has been presented. For the first time, regression equations of the relationship between exchangeable acidity pHKC1 and the degree of peat base saturation V, between total absorbed bases S and the degree of peat base saturation V have been obtained using nonlinear regression analysis. The adequacy and stability of the developed models have been verified. The calculated mean errors of approximation of regression models characterise the high accuracy of the forecast and are indicative of a good selection of models for the initial data.

Land suitability assessment of soils for rubber and cashew cultivation in the Coastal Area of Bodo City, Rivers State, Southern Nigeria

The research was carried out in Bodo city in Gokana Local Government of Rivers State, Southern Nigeria to evaluate the land suitability for rubber and cashew cultivation using the relevant land suitability guidelines for the cultivation of the two cash crops of interest. Mapping of the 100 ha of land in Bodo city was done using the rigid grid method of soil survey. The three mapping units (summit, middle slope and valley bottom) were identified and delineated. Three representative soil pedons of 2 m x 2 m x 2 m were dug and described by horizon from top to bottom (0 cm to 200 cm). Soil samples were collected from identifiable horizons and processed for laboratory analysis using standard routine laboratory methods most appropriate. The results showed that pedons 1 and 3 covering 86,000 ha of the entire study area were found to be moderately suitable for rubber cultivation with limitation in soil physical characteristics (texture) and fertility (low base saturation < 50 %). Pedon 2 covering 14,000 ha of the total land of the study area was marginally suitable due to limitation in soil fertility (low base saturation < 80 %). Pedon 1, 2, and 3 were also moderately suitable for cashew cultivation in the study area with limitation in soil physical characteristics (texture) and fertility (low organic carbon), while limitation in wetness (poor drainage) was peculiar to pedon 3 only. Thus, soils in the study area were moderately suitable for both rubber and cashew cultivation in the area.

Evaluation of soils with average potassium content summation for implantation of Musa sp in the municipality of Teotônio Vilela, Alagoas

Soil fertility is one of the crucial factors for agriculture, whose main objective is to increase production. Therefore it is extremely important to know the nutritional requirement of cultivars. Fertility-focused studies are essential for fertilization recommendations in all regions, especially in banana cultivation which is a very demanding plant in fertility. Thus, the present work aimed to evaluate soil fertility, emphasizing the quantification of nutrients necessary to ensure the agricultural productivity of musa sp. The research was developed at laudelino farm, municipality of Teotônio Vilela/Alagoas, between 2019 and 2020, where soil amotragens were performed, randomly collected in the 0-20 cm depth layer, removing 1 kg of soil and sent to the soil laboratory of the Campus of Engineering and Agrarian Sciences (CECA) of the Federal University of Alagoas (UFAL) located in the municipality of Rio Largo-AL, for chemical analysis. The hydrogenic potential (pH), phosphorus (P) and potassium (K+) accessible were analyzed; calcium (Ca+2) and tradable magnesium (Mg+2); saturation by exchangeable aluminum (m%), cation exchange capacity CTC at pH 7.0 (T); base saturation (V%) and; organic matter (OM). As a result of the analysis, the following results were obtained: pH content (5.6); OM (14.1 g/kg) P (5.0 mg/dm³) K (110 mg/dm³), Ca2+ (3.42 cmolc/dm³), Mg2+ (2.53 cmolc/dm³); Al3+ (0.00 cmolc/dm³), H (4.41 cmolc/dm³), and CTC (T) (10.73 cmolc/dm³); m (0.0 %) and V (59 %). Based on the above results, it is suggested the application of 1,103 kg of limestone in order to increase the base saturation to 70%, in addition to the addition of 50 kg/ha of N and 343.5 kg/ha of P2O5 and 96.7 kg/ha of K2O. It is worth mentioning that their applications in the soil must be carried out through sources of 837.8 kg/ha of triple superphosphate; 161.2 kg/ha of potassium chloride and 111 kg/ha of urea. It is also essential to add 30 to 50 t/ha of organic matter, such as bovine manure to the soil, aiming at better utilization of the material by crops.

Does forest tree species composition impact modelled soil recovery from acidic deposition?

Acidic deposition depleted soil base cation pools throughout central Ontario, particularly during the second half of the twentieth century. While sulphur (S) and nitrogen (N) deposition have declined in recent decades, forest harvesting may continue to remove base cations from soils, highlighting the need for reliable soil chemistry forecasts. This study investigated whether differences in soil chemistry among forest stands dominated by different tree species affected predictions using a dynamic biogeochemical model (VSD). Soil base saturation was modelled from 1850–2100 in stands dominated by balsam fir (<i>Abies balsamea</i> (L.) Mill.), eastern hemlock (<i>Tsuga canadensis</i> (L.) Carr.), white pine (<i>Pinus strobus</i> L.), sugar maple (<i>Acer saccharum</i> Marsh.), or yellow birch (<i>Betula alleghaniensis</i> Britt.). Three scenarios that manipulated future atmospheric S and N deposition and forest harvesting (2020–2100) were applied. When future atmospheric S and N deposition remained at 2020 levels and harvesting continued, base saturation increased marginally (2.0–4.5%) in all plots. Further increases in base saturation were minor (~1%) by 2100 when deposition reductions were implemented. When future forest harvesting was excluded, soil base saturation increased 3.4–8.5% from 2020–2100. These results suggest that tree species composition has minimal influence on modelled soil chemistry forecasts in response to changes in acidic deposition, and such models can be broadly applied for regional predictions.

A modification of land suitability requirements for maize in the humid tropics of South Sulawesi

Evaluation of land suitability needs to be supported by site-specific approach including criteria of the land use type. One of the important food crops in the humid tropic of Indonesia is maize (Zea mays L.). The main aim of this study was to modification land suitability requirements for maize in the specific humid tropic of Indonesia. There were 3 representative districts in the South Sulawesi of Indonesia, consists of Jeneponto (dry zone, climate type E), East Luwu (wet zone, climate type A), and Bulukumba (relative dry, climate type D). There were 20 profiles in each district so that total of representative are 60 farmers and 60 profiles. This study used the deductive parametric approach on determine land suitability index (based on crops yield), the determination of observation’s point was purposive sampling, data analysis was use Pearson correlation and linier regression analysis including on determination of interval value of land characteristics that have correlation and significant effect to maize yield. The result showed that land characteristics that have significant effect (p<0.01) to maize yield in the humid tropic of South Sulawesi were precipitation of growth cycle, soil pH, C-Organic, and base saturation. The range values of land characteristics which classified as optimal (S1) for humid tropic region of Indonesia were precipitation of growth cycle (650-900 mm), soil pH (6.8-7.0), C-organic ( >2.2%), and base saturation (>62%), furthermore classified as marginal (S3) whether precipitation of growth cycle(<270 mm), C-organic (<1.15%), soil pH (<5.47 or >8.0), and base saturation (10-41%).

Soil fertility status in tidal land of Tirtomarto reservoir, Central Java, Indonesia

Reservoir tidal land used for agriculture is generally done when the reservoir water level begins to shrink. This land is used as a moor in dryland or lowland rice fields in the wetland. The purpose of the study was to determine the soil fertility status of the tidal land of the Tirtomarto reservoir, Central Java. Parameters tested include cation exchange capacity (CEC); base saturation (BS); C-Organic; total soil P and K levels according to the technical instructions for evaluating soil fertility. Soil samples were taken from three location points by the purposive sampling method. The results showed that most of the soil samples contained low to very low nutrients, except for the total P content which had a high value. Therefore, the fertility status in the tidal land of the Tirtomarto reservoir, Central Java, can be categorized as low. The low fertility status of the soil at the study site was due to the limiting factors, namely the low C-organic content of the soil, low K total soil, and low cation exchange capacity and base saturation.