Sub-humid Environment Research Articles

Agronomic performance and nutritive value of Urochloa species, Desho and Rhodes grass grown in sub-humid central Ethiopia

Improved forage grasses with high quality and biomass are a crucial additional feed source for cereal-livestock farming in Ethiopia. This study compared the performance of 4 Urochloa species [U. brizantha (DZF-13379), U. humidicola (DZF-9222), U. decumbens ‘Basilisk’ (DZF-10871) and U. mutica (DZF-483)] with other 2 commonly used grasses, Rhodes grass (Chloris gayana ‘Massaba’) and Desho grass (Pennisetum glaucifolium local variety Kindu kosha), over 3 years during the main rainy season in Bishoftu in a sub-humid area of Ethiopia. The experiment was conducted using a completely randomized block design. There was significant variation among species for agronomic parameters. The species × year interaction was significant for dry matter yield, plant height, and plot cover but not significant for leaf-to-stem ratio. Nutritional value [ash, acid detergent fiber (ADF), crude protein (CP) and in vitro dry matter digestibility (IVDMD)] was significantly different among species with no differences for neutral detergent fiber (NDF) and acid detergent lignin (ADL). All species showed potential as alternative ruminant feeds with U. mutica and U. brizantha the highest yielding in the sub-humid environment.

Calibration and evaluation of a CROPGRO Perennial Forage Model for Brachiaria humidicola yield simulation under future climate in subhumid environments of Ethiopia

Crop simulation models can be employed to assess the impacts of climate change and aid in strategic planning and decision making regarding forage strategies. This study focused on calibrating and assessing the performance of the CROPGRO Perennial Forage Model in simulating Brachiaria humidicola yield under projected future climates for high and moderate representative concentration pathway (RCP) scenarios in the central and western subhumid regions of Ethiopia. The model was calibrated to accurately represent rainfed growth and biomass yield, using field data from the Debre Zeit and Bako Agricultural Research Centers. Climatic data, including rainfall, temperature and solar radiation, were sourced from weather stations, whereas future climate scenarios for the near future, mid-century and end-of-century periods were derived from the CORDEX Africa outputs under RCP 4.5 and RCP 8.5. The calibration process refined species parameters related to vegetative partitioning, and enhanced the d-statistic and reduced the root mean square error (RMSE) for herbage, leaf, stem and total biomass accumulation. Despite projected decreases in leaf biomass, stem biomass is projected to increase. In addition, there are projected increases in herbage and total biomass accumulation under elevated greenhouse gas concentrations and warmer temperatures. Ultimately, the projected climate under both RCPs had no significant effect on Brachiaria humidicola grass production in Ethiopia.

Abiotic Stress Effect on Agastache mexicana subsp. mexicana Yield: Cultivated in Two Contrasting Environments with Organic Nutrition and Artificial Shading.

Research on medicinal plants is essential for their conservation, propagation, resistance to environmental stress, and domestication. The use of organic nutrition has been demonstrated to improve soil fertility and plant quality. It is also important to study the effects of the Basic Cation Saturation Ratio (BCSR) approach, which is a topic where there is currently controversy and limited scientific information. Evaluating the growth and yields of Agastache mexicana subsp. mexicana (Amm) in different environments is crucial for developing effective propagation and domestication strategies. This includes examining warm and subhumid environments with rain in summer in comparison to mild environments with summer rain. Significant differences were observed in the effects of cold, waterlogging, and heat stresses on the plant's biomass yield and the morphometric-quantitative modeling by means of isolines. The biomass yield was 56% higher in environment one compared to environment two, 19% higher in environment one with organic nutrition, and 48% higher in environment two with organic nutrition compared to using only BCSR nutrition. In the second harvesting cycle, the plants in environment one did not survive, while the plants in environment two managed to survive without needing additional nutrition. Statistical and mathematical analyses provided information about the population or sample. Additionally, further analysis using isolines as a new approach revealed new insights into understanding phenology and growth issues.

Technical note: Isotopic fractionation of evaporating waters: effect of sub-daily atmospheric variations and eventual depletion of heavy isotopes

Abstract. Isotopic fractionation of evaporating waters has been studied constantly in recent decades, particularly because it enables calculation of both the volume of water evaporated from a water body and the isotopic composition of its source water. We studied the stable water isotopic composition of an artificial pan filled with water and subject to total evaporation in a sub-humid environment, in order to put into practice an operational method for estimating the time since disconnection of riverine pools when these are sampled for the quality of aquatic life. Results indicate that (i) when about 70 % of pan water had evaporated and its isotopic composition had become enriched in heavy isotopes, some subsequent periods of depletion instead of enrichment happened; and (ii) the customary application of isotopic fractionation equations to determine the isotopic composition of the water in the pan using weekly averaged atmospheric conditions (temperature and relative humidity) strongly underestimated the changes observed but predicted an early depletion of heavy isotopes. The first result, rarely reported in the literature, was found to be fully consistent with the early studies of the isotopic composition of evaporating waters. The second one could be attributed to the fact that weekly averages of temperature and relative humidity strongly overestimated air relative humidity during daylight periods of active evaporation. However, when the fractionation equations were parameterized using temperature and relative humidity weighted by potential evapotranspiration at sub-hourly time steps, they adequately reproduced the observed isotopic composition of the water in the pan, including the late periods of heavy isotope depletion. We demonstrate how weekly increases in air relative humidity when the pan water was already enriched in heavy isotopes led to their depletion. We also analyse the errors that can be incurred if time averages are used instead of flux-weighted meteorological data for model parameterization and if unidentified periods of heavy isotope depletion occur. Our results should be taken into account when applying fractionation equations, particularly in conditions or areas with high air relative humidity.

Effect of cover crops mixtures on weed suppression capacity in a dry sub-humid environment of Argentina

Cover crops (CC) are increasingly used worldwide within integrated weed management scenarios. They are usually established between two commercial crops and are not harvested, grazed, or incorporated into the soil, but remain on the surface during their growth cycle. The aim of this work was to determine the performance of different CC mixtures and their effects on weed suppression in the south-central region of Buenos Aires province, Argentina. Field experiments were carried out in 2019 and 2020 at the CEI Barrow (MDA-INTA, Tres Arroyos), where both binary and ternary CC mixtures were evaluated. Binary mixtures consisted of winter cereals (Avena sativa, Secale cereale) and legumes (Vicia villosa, Vicia sativa) while ternary mixtures were obtained by combining binary mixtures with canola (Brassica napus). Weed emergence counting was performed on a 14- day basis to determine weed total density. Vegetation cover of the CC mixtures as well as biomass production from crops and weeds were estimated. The specific composition of the mixtures showed a greater influence on vegetation cover than on biomass production, which would depend mainly on the prevailing environmental conditions. The type of vetch used, the addition of canola, as well as, the proportion of cereals in the mixture determined the CC effect on weeds. CC were consistently more effective in suppressing weed biomass than seedling emergence density. However, weed seedling suppression by CC was similar to or even greater than the chemical-based control (p<0.0001). The average biomass of weeds in all CC (pooled data) was highly reduced when compared to the weedy control (12 vs 259 g m-2, p<0.001), and similar responses were obtained when compared to the chemical fallow (8 g m-2). The mixture S. cereal+ V. villosa+ canola stood out for presenting the highest values of productivity and vegetation cover and high weed suppression. These results provide support for the choice of CC mixtures in a dry sub-humid area of Argentina, aimed at maximizing interference with weeds and also to demonstrate their benefits in short- and long-term management. Therefore, CC implementation within crop sequences should be considered as a complementary tool contributing to the development of more sustainable management strategies.

Reproductive performance of Horro and Horro-crossbred dairy cows in Ethiopia's subhumid tropical environments.

Estrus detection, timing of insemination, feeding, and health care practices are all factors that can significantly affect cattle breeding efficiency and lifetime production. In Ethiopia's subhumid environment, the age at first calving, number of days open, duration from calving to first heat, and number of services per conception are economic traits that affect reproductive performance of Horro and Horro-crossbred dairy cows. Data collected at Ethiopia's Bako Agricultural Research Center between 1980-2019 was used to study the reproductive performance of Horro and Horro-crosses with Holstein Friesian and Jersey dairy cows. We identified overall mean ± standard error values of factors that affect reproductive performance, including age at first service (AFS) (29.2 ± 0.2 months), age at first calving (AFC) (39.8 ± 0.2 months), number of services per conception (NSC) (1.76 ± 0.4 months), calving interval (CI) (13.2 ± 0.3 months), days open (DO) (94.3 ± 4.3 days), conception rate (CR) (75.0 ± 1.3%), and replacement rate (RR) (28.4 ± 0.3%). The odds ratios of the 60-day and 90-day nonreturn rates (NRR) were 0.22 and 0.96, respectively. Sire and dam breed and birth period had significant (P < 0.001) effects on AFS and AFC, while season and dam parity had significant effects on CI and DO. Inconsistencies regarding feeding, heat detection, inseminator skills, insemination timing, animal health, and other husbandry practices may extend periods of AFS, AFC, CI, and DO. To optimize reproductive performance in Horro cows and Horro crossbreeds in Ethiopia's subhumid environments, improving management practices should be a priority.

The macromoth fauna of a humid biotope in the Novara district (Piedmont, Northern Italy)

The authors detail a survey of macromoths carried out from 2015 to 2020 in the area of Torrion Quartara of the municipality of Novara (Piedmont, NW Italy). The site still retains many of the original vegetation characteristics of Po Valley, a factor which enabled the survival of numerous species linked to humid and subhumid environments that are greatly threatened nowadays by extensive farming, urban developments, and global warming, thus highlighting the need to carefully preserve the environmental integrity of such rare lowland remnant of primeval habitats once widespread in the area.

WATER USE EFFICIENCY OF TARO (Colocasia esculenta) UNDER VARYING WATERING REGIMES AND PLANTING DENSITIES IN EMBU, KENYA

&lt;p&gt;&lt;strong&gt;Background. &lt;/strong&gt;Taro (&lt;em&gt;Colocasia esculenta&lt;/em&gt;) can be grown in a variety of environmental and edaphic conditions, but it is most typically grown in wetlands. The optimal conditions for its growth are two water regimes i.e., waterlogged or flooded conditions to dryland or unflooded conditions. An important criterion in crop yield is water use efficiency (WUE), and it has been suggested that crop production per unit of water used can be increased. &lt;strong&gt;Objectives.&lt;/strong&gt; To determine the WUE of taro in Kenya’s sub-humid environment under different watering regimes and planting densities. &lt;strong&gt;Methodology.&lt;/strong&gt; A study was conducted at the Kenya Agricultural and Livestock Research Organization (KALRO) – Embu Research Centre, during the long rains (LR) 2021, short rains (SR) 2021/2022, and long rains (LR) 2022. A factorial experiment with a split-plot layout arranged in a completely randomized block design was used. The main factor was the irrigation levels while the sub-factor was the planting density, with three replications. The three irrigation levels were at 100 %, 60 %, and 30 % based on the field capacity (FC). The planting densities used were 0.5m × 0.5m (40,000 plants ha&lt;sup&gt;-1&lt;/sup&gt;), 1m × 0.5m (20,000 plants ha&lt;sup&gt;-1&lt;/sup&gt;), and 1m × 1m (10,000 plants ha&lt;sup&gt;-1&lt;/sup&gt;), representative of high, medium, and low planting densities respectively. &lt;strong&gt;Results.&lt;/strong&gt; The WUE was influenced by season and watering regime (&lt;em&gt;P &amp;lt; 0.05&lt;/em&gt;). The 30% FC had the highest WUE with the 100 % FC having the lowest. The high WUE under 30 % FC (19.40 kg ha&lt;sup&gt;-1&lt;/sup&gt;mm&lt;sup&gt;-1&lt;/sup&gt;) was associated with the high biomass (1.97 kg) and low water use (2269.41 mm) recorded under limited water conditions. The medium (1m × 0.5m) planting density attained the highest WUE (12.16 kg ha&lt;sup&gt;-1&lt;/sup&gt;mm&lt;sup&gt;-1&lt;/sup&gt;) with the high planting density (0.5m × 0.5m) having the lowest (10.65 kg ha&lt;sup&gt;-1&lt;/sup&gt;mm&lt;sup&gt;-1&lt;/sup&gt;), though no significant differences were recorded. &lt;strong&gt;Implications. &lt;/strong&gt;The&lt;strong&gt; &lt;/strong&gt;varying watering regimes and planting densities in this study have different capacities to utilize the supplied water. The total taro biomass increased with decrease in water supplied and in turn maximized the water use efficiency. &lt;strong&gt;Conclusion.&lt;/strong&gt; To achieve the highest yield per unit of water consumed, a watering regime of 30 % FC and a planting density of 1 m × 0.5 m (20,000 plants ha&lt;sup&gt;-1&lt;/sup&gt;) is recommended.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;div id="gtx-trans" style="position: absolute; left: 179px; top: 404.969px;"&gt; &lt;/div&gt;

Assessment of the impact of irrigation management on soybean yield and water productivity in a subhumid environment

As an effect of climate change, a considerable increase in irrigation demand is expected in subhumid regions. This poses a future challenge for agriculture, which often does not meet the requirements for highly efficient irrigation management. Field experiments in combination with modelling approaches can help in the development and evaluation of alternative irrigation strategies. The aim of this study was to parameterize the FAO AquaCrop model for soybeans in order to evaluate irrigation systems and strategies used by farmers in Austria. Moreover, this study aims at proposing a deficit irrigation strategy to increase irrigation water productivity (WPIrrig). Three irrigation methods were investigated: sprinkler, drip, and hose reel boom. Rainfed conditions were also assessed. Data sets from 2018 and 2019 were used for the parameterization of AquaCrop. Based on threshold values for the percentage of readily available water (RAW), full and deficit irrigation strategies were defined and tested for the years 1990–2019. The parameterization results showed good agreement between the simulated and observed canopy cover and yields from the four water management practices, with Nash-Sutcliffe efficiency coefficients between 0.76 and 0.96. Large errors resulted from the soil water content simulations, mainly due to poor sensor performance. It was concluded that a moderate deficit with RAW thresholds of 150% and 140% for the vegetative and reproductive stages, respectively, was an adequate strategy to improve yields and WPIrrig. Conversely, a severe deficit with an irrigation threshold of 180% RAW throughout the season considerably reduced yields, especially in years with high irrigation demand. Moreover, a significant improvement in WPIrrig was observed when drip systems were used compared to sprinklers, due to the higher efficiency of the former. These results can help scheduling irrigation for soybeans and increasing WPIrrig, thereby reducing pressure on limited water resources.

Updating Ecology and Distribution of Wild Truffles in Morocco

The distribution and abundance of the various truffle species are influenced by the climate, soil, and vegetation conditions. The setting of these characteristics is necessary for the potential species’ cultivation. Here, we describe the ecological characteristics of Moroccan truffles and desert truffles and their associations with host plants. We also determine the climate and soil parameters relating to the geographic distribution and fructification of truffles and desert truffles. In contrast to truffles, which are found in sub-humid environments, desert truffles are found in semi-arid and arid regions of Morocco. The dissemination of desert truffles in the Mamora forest and oriental regions of Morocco is typically linked to the presence of Helianthemum sp., whereas the existence of truffles (Tuber spp.) in the Middle Atlas depends on the subsistence of Quercus ilex and Q. faginea. The truffles’ and desert truffles’ fructification depends mainly on the precipitation frequency. Terfezia arenaria and Tuber oligospermum, the two major desert truffles of Mamora forest, require an annual rainfall of 435 mm on average in slightly acidic soil. While the oriental and Highland desert truffles, namely Terfezia boudieri, T. claveryi, and Tirmania spp., require an annual precipitation average of 123 to 267 mm and a high CaCO3 content. Otherwise, there is Tuber aestivum, localized in humid regions with a rainfall rate of more than 650 mm, and found under calcareous soil rich in organic matter with the presence of potential host plants, such as oaks, cedars, and pines. Our findings open up the possibility of successful cultivation of truffles and desert truffles having an economic interest through understanding their ecological requirements in Morocco.

Palustrine limestones and calcretes as the sedimentary record of paleoenvironmental changes in a Late Permian semi-arid climate at the SE periphery of the Southern Permian Basin (the Holy Cross Mountains, Poland)

An important part of the Upper Permian (Zechstein) sequence in the Holy Cross Mountains (HCM) in Poland comprises continental carbonate facies where dryland and wetland depositional environments dominated the southeastern part of the Southern Permian Basin. Sedimentological and thin-section microfacies analysis of over 860 m of core from seven wells, supplemented with field observations from several outcrops from the HCM area, has allowed recognition of numerous siliciclastic and mixed silici‑carbonate facies which are related to alluvial fan, proximal and distal floodplains, and ephemeral lacustrine environments. Due to climatic seasonality and subsequent groundwater oscillations, the latter were frequently exposed, causing widespread desiccation cracking and pedogenesis. Continuous aggradation controlled by steady tectonic subsidence allowed the deposition and preservation of thick (> 30 m) units with numerous palustrine intervals. In such a low aggradation rate system, vertical and lateral changes in the continental facies associations reflect the climatic evolution from arid to semi-arid and then to sub-humid environments with enhanced climatic seasonality. These facies changes indicate a gradual increase in the water availability towards the Permian-Triassic boundary, which may support the hypothesis of generally increased wetting at the low-latitudes of Pangea, linked with the development of greenhouse conditions and enhancement of the intertropical convergence zone at that time. Continental carbonates are therefore recognised as high-resolution recorders of palaeoclimate and tectonics.

Modelling and mapping of soil erosion susceptibility using machine learning in a tropical hot sub-humid environment

Sobha watershed , located in the Puruliya district of West Bengal, India, is experiencing severe soil erosion due to specific geo-environmental settings and unscientific land practices. It poses serious threats to agricultural and natural resource development, resulting in land degradation and desertification . This study attempts to identify soil erosion susceptible zones (SESZ) of the Sobha watershed by utilising remote sensing and GIS data products in different machine learning algorithms i.e., Support Vector Machine (SVM), Classification and Regression Tree (CART), Boosted Regression Tree (BRT), and Random Forest (RF)) considering sixteen soil erosion controlling factors (SECFs). In addition, the efficiency of the chosen machine learning models was evaluated using known soil erosion and non-erosion data. The results showed that elevation, drainage density (DD), and normalised difference vegetation index (NDVI) factors contribute the most to soil erosion. The ROC (receiver operating curve) AUC (area under the curve) is used to compare each model, and it was reveals that the RF model performed and predicted the best among them. However, all the models exhibit an outstanding capacity with AUC >85% (RF = 0.97, BRT = 0.96, SVM = 0.95, and CART = 0.88). The RF model results show that the Northeastern portion of the catchment (upper part) is most vulnerable to erosion, and about 14.48% of the basin areas are under the severe erosion zone. Thereby, the findings based on machine learning algorithms and intensive field visits are utilised to assess the soil erosion risk zones, and this work will give insight into implementing suitable policies to mitigate this issue. Furthermore, the approaches utilised in this study could be useful in predicting soil erosion risk in other regions as well. In addition, the study has also recommended some appropriate policies and management approaches that would be immensely useful for the local government and policymakers in initiating strategic planning to combat soil erosion.

Evaluation of artificial intelligence models for daily prediction of reference evapotranspiration using temperature, rainfall and relative humidity in a warm sub-humid environment

Accurate estimation of reference evapotranspiration is essential for agricultural management and water resources engineering applications. In the present study, the ability and precision of three artificial intelligence (AI) models (i.e., Support Vector Machines (SVMs), Adaptive Neuro-Fuzzy Inference System (ANFIS) and Categorical Boosting (CatBoost)) were assessed for estimating daily reference evapotranspiration (ET0) using limited weather data from five locations in a warm sub-humid climate in Mexico. The Penman–Monteith FAO-56 equation was used as a reference target for ET0 values. Three different input combinations were investigated, namely: temperature-based (minimum and maximum air temperature), rainfall-based (minimum air temperature, maximum air temperature and rainfall), and relative humidity-based (minimum air temperature, maximum air temperature and relative humidity). Extraterrestrial radiation values were used in all combinations. The temperature-based AI models were compared with the conventional Hargreaves–Samani (HS) model commonly used to estimate ET0 when only temperature records are available. The goodness of fit for all models was assessed in terms of the coefficient of determination (R2), Nash–Sutcliffe model efficiency coefficient (NSE), root mean square error (RMSE) and mean absolute error (MAE). The results showed that among the AI models evaluated, the SVM models outperformed ANFIS and CatBoost for modeling ET0. Further, the influence of relative humidity and rainfall on the performance of the models was investigated. The analysis indicated that relative humidity significantly improved the accuracy of the models. Finally, the results showed a better response of the temperature-based AI models over the HS method. AI models can be an adequate alternative to conventional models for ET0 modeling.

Vegetation Composition, Forage Biomass and Soil Seed Bank of a Continuously Grazed Rangeland Site in Tropical Sub-Humid Environment, Tanzania

Most rangelands along the agro-pastoral villages of Tanzania are yearlong grazed and at various states of degradation. These rangelands contribute to over 60% of the meat and milk production in the country. An inventory was conducted to assess the status of grazing resources in a typical agro-pastoral village of Tanzania having communal rangelands. Systematic random sampling techniques were employed whereby line transects and quadrat frame were used following standard procedures to collect samples and undertake field measurements for both vegetation and soil parameters. The vegetation cover for desirable pasture species, undesirable pasture species and litter were 67.7%, 10.5% and 9.4%, respectively. The soil bare patches covered 12.3 % of the surveyed rangeland site. The most dominant grass species were Enteropogon macrostachyus, Bothriochloa insculpta and Heteropogon contortus. Forage dry matter (DM) yield was 806.8 kg DM/ha. Tree density was 1500 trees/ha and the total canopy cover was 63.49%. Combretum collinum was the most dominant tree species. Soil bulk density, pH, organic carbon, nitrogen, phosphorus and potassium were 1.4 g/cm3, 6.3%, 1.14%, 0.09%, 0.89 mg/kg and 0.33 g/kg, respectively. A total of 11 dicotyledonous species mainly forbs and 9 monocotyledonous species including two perennial grasses were revealed from the incubated soil samples. The findings of this study demonstrate that the communal grazing areas have low pasture productivity, poor soil seed-bank and high cover of woody plants mainly bushes. In order, to improve forage biomass at the study site and elsewhere with similar environments selective bush clearing and re-seeding should be considered.

Effect of Wheat Monoculture on Durum Wheat Yield under Rainfed Sub-Humid Mediterranean Climate of Tunisia

Cultivating cereals in monoculture systems contributes to the decrease in grain yield and quality. Currently, under Mediterranean climate conditions of Tunisia, wheat mono-cropping covers more than 70% of cereal areas. In order to reveal the impact of this practice on cereal productivity, five improved durum wheat cultivars (Karim, Khiar, Om Rabiaa, Razzek, and Maali) were conducted under two conditions of previous wheat crop: one-year wheat previous crop (W) and two successive years (W-W). Then, they were assessed for grain yield (GY), yield components (NKS, TKW, NS), straw yield, harvest index (SY, HI), and grain quality parameters during three consecutive cropping seasons (2017, 2018, and 2019). The results showed significant effects of cropping season for all measured parameters, except thousand kernel weight (TKW). A significant effect (p &lt; 0.05) of Pre-Crop was observed on yield components. However, grain yield (GY) was improved after one-year wheat Pre-Crop (W) (4082.3 kg ha−1) more than after two years (W-W) (3277.3 kg ha−1). Our results show that, based on the three-year experiment, almost all yield related traits were significantly affected by the genotype except HI and NS. The highest GYs were recorded for Om Rabiaa (4010.4 kg ha−1) and Nasr (3765.76 kg ha−1). All grain quality was significantly (p &lt; 0.05) affected by cropping season, but only gluten content (GC) and vitreousness aspect (Vit A) were affected by genotype. On the other hand, the Pre-Crop W-W decreased grain protein concentration (GPC) (12.13%) and GC (22.14%) but no significant effect was observed on the Vit A of grain in our study. Furthermore, GY was positively correlated with HI (r = 0.64), NKS (r = 0.59), SN (r = 0.49), GPC (r = 0.23), and GC (r = 0.23). According to stability analysis, the Karim cultivar is the most stable genotype in wheat mono-cropping for GY and straw yield (SY). Altogether, this study provides useful information for farmers on how to produce a satisfactory yield for durum wheat cultivation under mono-cropping wheat conditions in the sub-humid environment of the Mediterranean climate of Tunisia.

Corrosion and Aging Behavior of Epoxy/Polyurethane Coatings on Carbon Steel in a Subhumid Environment

Corrosion and Aging Behavior of Epoxy/Polyurethane Coatings on Carbon Steel in a Subhumid Environment

Impact of heat stress on reproductive performances in dairy goats under tropical sub-humid environment

Reproductive parameters of dairy animals are generally affected by meteorological factors. This study aimed to investigate the effects of heat stress (HS) on reproductive parameters Saanen and Saanen× Red Maradi (½S½RM) dairy goats reared on a private farm in a tropical sub-humid environment in Benin. To assess the reproductive performances 103 goats (46 Saanen and 57 ½S½RM) were followed up from January 2015 to December 2019. The temperature-humidity index (THI) was obtained during the same period using meteorological data such as ambient temperature (AT) and relative humidity (RH). Pearson correlation matrix analysis was then performed between the environmental variables and the reproductive parameters. Reproductive parameters of ½S½RM goats were better than those of Saanen goats. The conception (92.09%), prolificacy (156.54%) and fecundity (117.11%) rates of ½S½RM goats were significantly higher than those of Saanen goats (67.16%; 149.41% and 89.70%). The conception rate of Saanen goats was not affected by the level of THI. The conception, prolificacy, and fertility rates of ½S½RM goats decreased from 97.22%, 161.35% and 121.52%, at moderate THI to 83.89%, 148.86%, and 110.04% at extreme THI, respectively. In summary, although Saanen goats were very efficient in milk production, their reproductive performance was affected by the level of THI. On the contrary, the ½S½RM crossbred goats had a better conception, prolificacy and fertility rates in the sub-humid tropical climate of Benin.

Coal mining in sub-humid forest : effect on microbial biomass Carbon, Nitrogen, Phosphorous and Nutrient flux

The effect of open-cost mining for coal on microbial C, N and P in sub-humid tropical forest environment was determined. The mining activities have resulted in 64-98% decline in plant biomass and 67 to 73% in microbial nutrients in barren spoils. The decline in soil organic matter was 60-84% in these spoils. Revegetation of theses spoils resulted in 9-14 times increase in plant biomass and 1.5 to 5 times in soil nutrients. Also microbial nutrients increased 2.5 to 3 times in revegetated sports as compared to barren dumps.

Organic soil fertility amendments enhance surface-dwelling beetle diversity in a sub-humid tropical environment under conservation agriculture

ABSTRACT Surface-dwelling beetles offer ecosystem services in agro-ecosystems including biological pest control and organic matter decomposition. This study was conducted to investigate beetle community response to six years of tillage, crop residue application, crop rotation and soil fertility amendments (low fertiliser, high fertiliser, manure, manure + low fertiliser and manure + 60 kg N ha−1) treatments. Reduced tillage increased beetle abundance by 4.6% relative to soil inversion tillage. Crop residue application increased the abundances of Platynus assimilis, Zophosis boei and total beetles by two to three times. Meanwhile, Renatiella reticulata increased by 628.6% in high fertiliser compared to manure + 60 kg N ha−1, manure + low fertiliser and the control. In crop rotation + crop residue retention plots, application of sole manure at 10 t ha−1 increased the Shannon index by 360–365% relative to manure + 60 kg N ha−1 and manure + low fertiliser. Based on the findings in this study, it can be concluded that reduced tillage, retention of crop residues on the soil surface and application of manure increase surface-dwelling beetle abundance and diversity.

INVERTEBRATE AND PLANT TRACE FOSSILS FROM THE TERRESTRIAL LATE TRIASSIC OF ZIMBABWE

ABSTRACT Late Triassic invertebrate and plant trace fossils are described from the Pebbly Arkose Formation of the Upper Karoo Group (Gwembe Sub-basin, Mid-Zambezi Basin), Zimbabwe. These ichnofossils appear in pedogenically modified siltstone and silty mudstone floodplain deposits and overbank fluvial channels. The ichnofossil-bearing sites show variability in their pedogenic features, maturity and preservation. Invertebrate ichnofossils are primarily recorded as horizontal, vertical and inclined burrows, sometimes branched, lined or unlined and may have an active meniscate infill. The common forms documented are Taenidium, Beaconites, Palaeophycus, Skolithos, and Planolites ispp. with some rare and more unusual morphologies (i.e., ‘Y’-shaped burrow type). Ichnofossil-bearing sites show a low-diversity but high-density of traces commonly dominated by Taenidium and Planolites ispp. The greatest diversity of invertebrate ichnofossils are within interbedded overbank sandstones in weakly pedogenically modified overbank sites. Rhizohalos and rhizoliths are common and often include carbonate infilled roots. Given the abundance and dimensions of fossilized wood and the rhizohalos and rhizoliths, the Pebbly Arkose Formation supported both large and small stature plants. Overall, the studied Pebbly Arkose Formation overbank areas are typically well-drained, calcic palaeosols subject to variable discharge, subaerial exposure, and supporting a diversity of plant and invertebrates tracemakers that lived in a semi-arid to sub-humid environment.