Grass Growth Research Articles

Impact of Biochar on Pathogenic Bacteria and Bermuda Grass (Cynodon dactylon) Growth in Soil Treated with Chicken Manure

Chicken manure plays an important role in soil amendment by improving soil properties for plant growth. However, the high levels of pathogens can have an adverse effect on humans when used for sports turf. This study was conducted to 1) determine the pathogenic bacteria in chicken manure-amended soil, 2) identify the appropriate decomposition stage of manure associated with reduced number of pathogenic bacteria, 3) assess the effect of different rates of biochar on pathogenic bacteria in the amended soil and 4) determine the effect of biochar on the growth of Bermuda grass. The design used for the laboratory experiment was 3˟3 factorial in Completely Randomised Design (CRD) and it was replicated three times. The factors involved were: decomposition stages of chicken manure (3 levels) and the different rates of biochar (3 levels). The best combination of biochar and chicken manure at the percentages of 0, 5, 10, and 15 were then used together with soil and sand mix at a ratio of 100:00 and 70:30 to plant Bermuda grass. This experiment showed that E. coli was present in chicken manure and that increasing the decomposition period had a significant effect on the E. coli by reducing its load. Also, the addition of biochar to the chicken manure resulted in a significant reduction of E. coli count (p<0.01). The soil amended with the biochar and manure also supported very well the growth of Bermuda grass with the 10% and 15% biochar manure mix in 70 to 30 ratio of topsoil and sand giving the best grass growth in terms of spread, thickness, height, and color. A regression analysis given by the equation Y(coverage)=176.857-23.0402(sprouting) (R2=0.99), indicated that sprouting significantly affected grass coverage such that 99% variation in the grass coverage was attributed to the sprouting. At the end of the study, it was concluded that well-composted chicken manure should be used together with biochar on sports fields to help remediate the problem of E. coli infestation and also improve the growth of grass on fields. Furthermore, biochar with chicken manure-amended soil could be ideal for vegetable garden to help reduce foodborne diseases caused by E. coli infestation.

Soil physical properties in a oxisol under a syntropic agroforestry system: row versus inter-row

Synthropic agroforestry systems are agricultural systems designed to reconcile agricultural production with environmental conservation. However, the benefits related to soil physical properties of these systems have only been documented for the planting rows. Thus, the physical behavior of the soil in the inter-rows remains unknown. The objective of this paper was to characterize the physical properties of the soil in the rows and inter-rows of a syntropical agroforestry system - SAS. For this, infiltration capacity (mini-disk infiltrometer) and soil resistance to penetration (STOLF Penetrometer) were measured in five ramdomly located blocks involving the rows and inter-rows. The results showed that there were no significant differences between row and inter-rows for both variables. The high species diversity, continuous addition of organic matter to the soil via pruning, the absence of heavy machinery use, and the vigorous growth of exotic grasses in the inter-row are the likely factors that explain the absence of differences reported here. We conclude that the rows and inter-rows of a SAS behave similarly in relation to the attributes evaluated. This demonstrates that such systems are highly beneficial for food production as well as maintaining soil physical properties.

A Hybrid Model that Combines Machine Learning and Mechanistic Models for Useful Grass Growth Prediction

Recently, Machine Learning (ML) has been heralded as a panacea for modelling problems across many domains, including Smart Agriculture (SmartAg), often in opposition to traditional mechanistic models arising on decades of scientific discovery. However, mechanistic models are often successful in “real world” problem-domains where ML models encounter difficulties (e.g., where the distribution of test data is not the same as the training data, violating the so-called identical and independently distributed (i.i.d.) assumption). In this paper, we consider a specific case of this opposition between a mechanistic model of grass growth and a ML model using historical, farm measurements. In our analyses, we find that both types of model have respective strengths. The mechanical model can often handle out-of-distribution events better than ML model, but the ML model can often handle temporary fluctuations in event variables (e.g., changing climate factors). Hence, we propose a combined hybrid model that learns which model to use when predicting grass growth. We argue that this combined approach has several practical benefits in providing stable and accurate predictions under widely varying conditions such as never before seen temperature fluctuations.

Nitrogen and phosphorus availability alters tree‐grass competition intensity in savannas

Abstract Plant essential macronutrients like nitrogen (N) and phosphorus (P) can limit savanna tree growth and are important determinants of savanna vegetation dynamics, along with rainfall, fire and herbivory. How nitrogen and phosphorus shape tree‐grass competition and their coexistence remain unclear, hindering our ability to predict how savannas may respond to altered nutrient cycling. Here, we evaluate (1) if trees and grasses respond differently to N versus P availability, or (2) if grasses are more competitive in low nutrient environments while trees are more competitive in high nutrient environments. To do this, we grew saplings of 6 tree and 1 grass species from the Kruger National Park, South Africa, for 16 weeks under fully factorial nutrient and competition treatments (with/without competitors, low/high rate of N supply and low/high rate of P supply) under a watering regime designed to mimic wet season rainfall in a mesic savanna. Trees and grasses foraged most aggressively for nitrogen and allocated biomass differently depending on nitrogen availability. Overall, tree growth decreased in competition with grass, even in high nutrient environments where they grew faster. Grasses were always better below‐ground competitors, utilising aggressive nutrient foraging strategies, including high root phosphatase activity in response to nitrogen and large root biomass allocation. Synthesis. In low nutrient environments (e.g. on nutrient‐poor sandy soils), nutrients may limit tree growth. Nutrient rich environments enable tree growth, but grasses continue to compete effectively with trees. Understanding what this means for ecosystem responses to nutrient availability is not trivial, especially in the context of fire and herbivory. However, it is clear that soil nutrients likely affect tree and grass growth and competition in savannas, which suggests that future changes in nutrient cycling, such as N deposition, may have important effects on savanna vegetation.

Effects of litter amount and seed sowing position on seedling emergence and growth of hemiparasitic Rhinanthus species under drought stress.

Roadside vegetation in Central Europe is mostly species-poor and dominated by a few grass species. Hemiparasitic plant species, including Rhinanthus spp., might effectively restrict grass growth, thereby making space for light-dependent herb species. Despite the significance of abiotic site conditions for plant establishment in general, their effects on Rhinanthus establishment are less well known. We investigated combined effects of water availability, litter amount and seed position within litter on Rhinanthus seedling emergence and growth. Two parallel greenhouse experiments were conducted with R. angustifolius and R.minor. In these, we tested the impact of 200 or 400 g litter·m-2 with seeds sown beneath or on top of a litter layer under constantly humid or intermittently dry conditions on seedling emergence and biomass production of Rhinanthus. Presence of litter positively affected Rhinanthus seedling emergence when sown beneath the litter layer and reduced negative effects of water deficiency. Sowing beneath a litter layer increased seedling emergence by 157%, with similar effects at 200 and 400 g litter·m-2. Water level did not affect biomass production. Compared to R.minor, R. angustifolius had higher mean biomass, and its seedlings emerged earlier and in higher numbers. Our results indicate that Rhinanthus spp. react similarly to litter as non-hemiparasitic plant species from temperate grasslands. Litter presence positively influenced Rhinanthus seedling emergence and growth under intermittently dry conditions. Its hemiparasitic characteristics might reduce drought impacts on biomass production. To ensure seed contact with the soil surface, seeds should be sown when no litter is present, or mulching should occur post-sowing.

Identifying favourable conditions for farm scale trafficability and grass growth using a combined Sentinel-2 and soil moisture deficit approach

In Atlantic Europe, on poorly drained grasslands soils, compaction negatively affects soil health when trafficked in wet conditions, while optimum grass growth cannot be achieved in excessively dry conditions. In Ireland, daily soil moisture deficit (SMD) information is forecasted at regional scale for all soil drainage classes. Optimal paddock conditions can occur between trafficking (10 mm) and optimum grass growth (50 mm) SMD thresholds for an identified drainage class. The objective of this farm scale study is to improve the identification of optimum conditions in time and space by combining high resolution spatial soil moisture estimates with soil drainage class specific SMD data. For that purpose, Sentinel- 2 (S-2) data was used in a modified Optical Trapezoid Model (OPTRAM) to derive normalised surface soil moisture (nSSM) estimates at farm level. In-situ soil moisture sensors providing daily estimates of volumetric soil moisture were used for validation of OPTRAM with an RMSE of 0.05. Cumulative 7-day SMD prior to the date of each S-2 image was analysed for each year from 2017-2021 to select nSSM maps corresponding to negative, 0 or −0 and positive SMD. Results established a relationship between nSSM and SMD indicating optimal conditions changed spatially and temporally. The months of April, May, August and September always presented at least 35% of the farm area available for optimum management operations. Future refinement of this methodology utilising daily high resolution remote sensing data could provide near real-time information for farmers.

The effect of caraway oil-loaded bio-nanoemulsions on the growth and performance of barnyard grass and maize

A proper formulation is crucial to improve the herbicidal effects of essential oils and their selectivity. In this study, we investigated the physicochemical properties of bio-based nanoemulsions (CNs) containing several concentrations of caraway (Carum carvi) essential oil stabilized with Eco Tween 80, as a surfactant, maintaining 1:1 proportions. Detailed physicochemical characteristics of the CNs revealed that their properties were most desired at 2% of the oil and surfactant, i.e., the smallest droplet size, polydispersity index, and viscosity. The CNs caused biochemical changes in maize and barnyard grass (Echinochloa crus-galli) seedlings, however, to a different extent. Barnyard grass has overall metabolism (measured as a thermal power) decreased by 39–82% when exposed to the CNs. The CNs triggered changes in the content and composition of carbohydrates in the endosperm of both species' seedlings in a dose–response manner. The foliar application of CNs caused significant damage to tissues of young maize and barnyard grass plants. The effective dose of the CN (ED50, causing a 50% damage) was 5% and 17.5% oil in CN for barnyard grass and maize tissues, respectively. Spraying CNs also decreased relative water content in leaves and affected the efficiency of photosynthesis by disturbing the electron transport chain. We found that barnyard grass was significantly more susceptible to the foliar application of CNs than maize, which could be used to selectively control this species in maize crops. However, further studies are needed to verify this hypothesis under field conditions.

Growth, yield and economics of fodder grasses at Prayagraj, Uttar Pradesh

To study the growth, yield and economics of fodder grasses at Prayagraj in Uttar Pradesh, experiment was established in July 2022 with three treatments and five replications. In this study planted three fodder grasses viz., Pennisetum purpurmum × Pennisetum typhoides (Hybrid napier), Brachiaria mutica (Para grass) and Stylosanthes hamata (Stylo). Results indicated that the maximum height was found in T1: Hybrid Napier 186.60 cm followed by T2: Para grass 132 cm and minimum in T3: Stylo 57 cm. The plant population was maximum found in T3: Stylo 16 followed by T1: Hybrid Napier and T2: Para grass 4 whereas number of tillers or branches per meter square found maximum in T3: Stylo 159.80 followed by T1: Hybrid Napier 158.60 and minimum in T2: Para grass 120. The green fodder yield and dry fodder yield was maximum found in T1: Hybrid Napier 860.16 and 266.65 qha-1 followed by T2: Para grass 438.77 and 122.86 qha-1 and minimum in T3: Stylo 194.65 and 36.98 qha-1 respectively. The maximum net return was found in T1: Hybrid Napier Rs. 75,660 followed by T3: Stylo Rs. 62.505 and minimum in T2: Para grass Rs. 61,605. The maximum B:C ratio was found in T1: Hybrid Napier 2.86 followed by T3: Stylo Rs. 2.61 and minimum in T2: Para grass Rs. 2.29.

PENGARUH KOSENTRASI PLANT GROWTH PROMOTING RHIZOBACTERIA (PGPR) TERHADAP JUMLAH ANAKAN DAN PANJANG DAUN RUMPUT GAJAH KERDIL ( Pennisetum purpureum CV. Mtt )

Providing PGPR to the soil around the plant can influence the growth and fresh production of Pygmy Elephant grass. This research aims to determine the effect of PGPR Mutiara Alam Tani on the number of tillers and leaf length. The research was carried out experimentally using (RAL) with 5 treatments and 4 repetitions consisting of treatment PO = Dwarf Elephant Grass (control) without the addition of PGPR; Treatment P1 = Dwarf Elephant Grass + PGPR 2.5 ml/liter water/m2; Treatment P2 = Dwarf Elephant Grass + PGPR 5 ml/liter of water/m2; Treatment P3 = Dwarf Elephant Grass + PGPR 7.5 ml/liter of water/m2; Treatment P4 = Dwarf Elephant Grass + PGPR 10 ml/liter water/m2). The parameters measured are the number of tillers and leaf length. The results showed that the highest number of tillers was shown in the P4 treatment where 10 ml of PGPR was added in 1 liter of water producing an average number of 5.50 tillers, while the lowest number of tillers was in the P0 treatment which did not add PGPR which produced an average number of tillers. 4.25 tillers. The longest leaves were found in treatment P4 where 10 ml PGPR was added in 1 liter of water with an average length of 75.75 cm, while the shortest leaf length was found in treatment P0 where no PGPR was added resulting in an average weight of 64.75 cm. The results of the analysis showed that the administration of PGPR Mutiara Alam Tani had no significant effect (P>0.05) on the number of tillers and leaf length of Dwarf Gajah Grass. Based on the results of the analysis of variance, it showed that P0, P1, P2, P3 and P4 had the number of tillers and leaf length which is relatively the same. So it can be concluded that the provision of PGPR Mutiara Alam Tani has not been able to influence the number of tillers and the yield of Dwarf Gajah Grass leaf length.

Quest to find compromised spatial and temporal resolutions for integrating remote sensing data with an agro-ecosystem model for grasslands

This paper addressed one of the main challenges in assimilating remote sensing derived variables into process-based crop model simulations, which is the inconsistent spatial and temporal resolution between information obtained from remote sensing and the outputs of process-based agroecosystem model. We proposed an applied method to reduce the number of required simulations by identifying (i) optimal points in time where additional information from remote sensing has the largest positive influence on the model performance and (ii) options to cluster 10 m grid cells to larger cells without compromising their information content. The MONICA (Model for Nitrogen and Carbon) model was applied to simulate above and below ground biomass in two grassland sites located in southern and eastern parts of Germany. The model was calibrated using LAI values obtained from Sentinel-2 and the sensitivity of output variables to two key root parameters (Root Form factor and specific root length) was evaluated. Our results showed that one or two satellite images covering the critical time periods right after cutting events significantly improved the predictions of grass yields produced by a mechanistic agroecosystem models (by up to 30 %). A larger number of images at other grass growth stages would not further improve the predictive power of the model. We also found that the sensitivity to these critical time periods was independent of model parameters. The mixed-resolution scheme (between 10 and 50 m) achieved better results compared with the high-resolution standalone state-updating method, yet it reduced computational costs by more than 50 %. In conclusion, we proposed a methodology to reduce the number of required simulations for data assimilation by aggregating data from fine to coarse resolutions. Our method was promising for applying data assimilation over large areas and benefiting more from satellite information for real-time prediction of agricultural productivity.

Growth of Urochloa grass in an oxisol treated with powdered silicate materials

An experiment was carried out in pots with a soil mixed with six powdered silicate materials originated from mining (kyanite, biotite schist, biotite syenite, basalt, vermiculite, or bentonite). These sources were mixed in 4.4 kg of soil (Anionic Acrustox) at the rates of 0 (control), or 440 g of ground silicate materials, in pots where Urochloa decumbens cultivar Basilisk was grown. The grass growth followed the relative total dry mass (%): 100 > 93.8 > 82.7 > 71.4 > 54.4 > 9.4 > 6.8 for biotite schist, bentonite, vermiculite, basalt, syenite, kyanite, and soil (control), respectively. Soil pH (6.5) ultimately decreased Mn availability to plants. Although some silicate materials increased Mn availability to plants, increasing treated plants growth, it was not possible to evaluate if plants were able to acquire more P when treated with silicate materials. Concentrations of Fe and P extracted from the soil and from shoots were highly correlated with dry mass. The reactivity of these materials in soils increasing soil pH may be an important parameter for ranking agrominerals, as the availability of nutrients was correlated to the amount of carbonate used to increase pH of the treated soil to 6.5.

GROWTH AND PRODUCTION OF MINI ELEPHANT GRASS IN POST-MINING LAND THAT IS FERTILIZED WITH MANURE


 
 
 Mini elephant grass is a forage for livestock that has high production and nutritional quality. Post-coal mining land is land that has a very low fertility rate. This study aims to determine the optimum dose of cow manure for the growth and production of mini elephant grass in post-coal mining land. This research was carried out in the post-mining area of PT Arutmin Indonesia Site Satui. This study used a completely randomized design with four treatments and five replications. The experimental treatment was a cow manure dose of 0 tons/ha (control) (P0), 5 tons/ha (P1), 10 tons/ha (P2), and 15 tons/ha (P3). The variables observed were plant height, number of tillers, leaf length, and production of fresh and dry matter. The data obtained were analyzed using the SPSS Ver.21 program. The application of cow manure significantly (P<0,05) increased the growth and production of mini elephant grass in post-coal mining land. The optimum dose of cow manure to increase the growth and production of mini elephant grass in post-mining land is 10 tonnes/ha which will produce 16.46 tillers per clump, plant height 52.33 cm, leaf length 49.33 cm, fresh forage production 2.4 tons/ha and dry matter production 0.53 tons/ha.
 
 

The distance from tree legumes in silvopastoral systems modifies the litter in grass-composed pastures

AbstractThe use of silvopastoral systems with tree legumes is a viable alternative to recover and develop pastures, as they add N to the system influencing pasture growth. This study hypothesized that the herbage and litter of signalgrass (Urochloa decumbens Stapf) is affected by legume trees in the pasture. Treatments were composed of (1) signalgrass + Mimosa caesalpiniifolia Benth.; (2) signalgrass + Gliricidia sepium Jacq.; and (3) signalgrass monoculture. The 3-year experiment followed a randomized complete block design with three replications. Tree legumes were planted in double rows (15 × 1 × 0.5 m), in 1 ha paddocks. Litter samples were taken in five distance points (0, 1.8, 3.7, 5.6 and 7.5 m) perpendicular to tree legume rows. Signalgrass was taller at longer distances from the trees (P < 0.05). Signalgrass height differed between treatments, with taller signalgrass found in pastures mixed with G. sepium (15.6 cm) compared to M. caesalpiniifolia (9 cm) (P < 0.05). Herbage N content decreased with increasing distance from tree rows (P < 0.05). Litter N content followed a similar pattern, ranging from 23 g/kg under the trees to 12 g/kg at 7.5 m away from tree rows. Signalgrass did not grow under the tree crown (0–1.8 m), especially when intercropped with M. caesalpiniifolia. The findings of this study suggest that the type of legume trees used in the silvopastoral system has the potential to modify the pattern of grass growth and content of N in pasture litter.

An inventory of grassland use on horse farms

An inventory of grassland use on horse farms

Nickel Effects on Growth and Phytolith Yield of Grasses in Contaminated Soils

Nickel (Ni) is extremely toxic to plants at high concentrations. Phytoliths have the potential to sequester the heavy metals absorbed by plants and act as a detoxification mechanism for the plant. The authors of the present study aimed to evaluate the effects of Ni on the growth and phytolith yield of grasses in two artificially contaminated soils. Two experiments separated by soil types (Typic Quartzipsamment and Rhodic Hapludox) were conducted in a completely randomized design in a 2 × 4 factorial scheme with three replications. The factors were two species of grass (Urochloa decumbens and Megathyrsus maximus) and three concentrations of Ni (20, 40, and 120 mg kg−1) and control treatment. The grasses were influenced by the increase in Ni rates in the soils. Ni exerted a micronutrient function with the addition of 30 mg kg−1 of Ni in soils, but this concentration caused toxicity in grasses. Such a level is lower than the limits imposed by the Brazilian environmental legislation. Higher Ni availability in Typic Quartzipsamment promoted Ni toxicity, with reduced growth and increased phytolith yield in the shoot, increased Ni in the shoot, and Ni occlusion in phytoliths by grasses, in comparison with Rhodic Hapludox. The yield and Ni capture in phytoliths by grasses in Ni-contaminated soils are related to the genetic and physiological differences between grasses and Ni availability in soils. Ni capture by phytoliths indicates that it may be one of the detoxification mechanisms of Urochloa decumbens to Ni contamination, providing additional tolerance. Megathyrsus maximus may be a future grass for the phytoremediation technique in Ni-contaminated soils.

Analysis of the growth of Chetumal grass established in a tropical climate

Objective: To evaluate the growth of Chetumal grass (Urochloa humidicola CIAT 679), in order to determine the optimal moment for the first harvest.
 Design/Methodology/Approach: A completely randomized experimental block design, with measurements repeated over time, and three repetitions was used. Morphological composition (MC), growth rate (GR), plant height (PH), intercepted radiation (IR), leaf:stem ratio (L:S), leaf:no-leaf ratio (L:NL), and aerial biomass (AB) —as well as leaf biomass (LB), stem biomass (SB), dead material (DM), net growth (NG), and total biomass (TB)— were evaluated every fifteen days, except for the two first samplings, which were carried out on a monthly basis. Data were analyzed using the GLM procedure of the SAS software and Tukey’s mean comparison test (α£0.05).
 Results: The morphological composition (MC) of the Chetumal grass was statistically different (p<0.05), during the different growth ages. The maximum accumulation of total biomass (TB) (13,324 kg DM ha-1), leaf biomass (LB) (2,569 kg DM ha-1), and growth rate (GR) (99 kg DM ha-1 d-1) was reached at 135 DAS. On that day, the prairie reached a 68 cm plant height (PH) and 100% intercepted radiation (IR). The L:S ratio decreased from 1.62 to 0.31, while L:NL ratio changed from 1.62 to 0.22.
 Study Limitations/Implications: The Brachiaria humidicola cv. Chetumal grass reached its highest potential during the rainy season.
 Findings/Conclusions: The first cut of the Urochloa humidicola cv. Chetumal grass can be carried out at 135 DAS, when the highest accumulation of total biomass (TB), leaf biomass (LB), and growth rate (GR) is recorded.

SustAinimal Grazing Living Lab – a survey of grazing management on dairy farms in northern Sweden

ABSTRACT A survey was conducted on 302 Sweden dairy farms (response rate 98%) to identify grazing and grassland management strategies and main challenges to grazing in northern Sweden. The most common grazing strategy on all dairy farms was continuous grazing (59%) followed by rotational grazing (45%), while organic dairy farms preferentially adopted rotational grazing (69%). The main challenges reported in grazing dairy cows on temporary grasslands on conventional farms were trampling damage and seasonal variations in grass growth, while for organic dairy farmers, the primary challenge was weed control. Only a few farms had grazing on semi-natural grasslands. Future sustainable grazing should focus on optimising grazing strategy in relation to on-farm grazing locations and nutrient supply for high-yielding dairy cows.

Contrasting Phosphorus Build-up and Drawdown Dynamics in Soils Receiving Dairy Processing Sludge and Mineral Fertilisers

Sustainable utilisation of waste from the food industry is required to transition to a circular economy. The dairy industry relies on high phosphorus (P) inputs and produces large quantities of P-rich dairy processing sludge (DPS). Recycling DPS into P fertilisers provides an opportunity to decrease the reliance on chemical P fertilisers. However, current soil nutrient management planning (NMP) is based on chemical P and does not account for recycled alternatives. A pot trial using a novel isotope pool dilution technique was used to describe build-up and drawdown cycles of P in soils fertilised with DPS. Changes in available, exchangeable, and Mehlich3 P (M3-P) pools were recorded over 36 weeks of grass growth. Results demonstrated that in the period of high P demand (12 weeks), these P pools were depleted. As crop growth and demand decreased, available P recovered through mobilisation of P from exchangeable P and M3-P reserves. DPS allowed available P to recover and build up to agronomic target levels after 24 weeks. Using DPS, build-up of available and exchangeable P was slower but P use efficiency was higher at stages of slow growth. Dairy waste created a more stable P pool which could be utilised by crops over a growing season indicating that NMP needs to account for this in the decision support for growers. Isotope studies revealed that extractive agronomic tests do not capture drawdown in P reserves.

Comparative Analysis of Precast and In situ Concrete and Their Effectiveness on Koga Irrigation Structures

Most construction projects in Ethiopia are built by using conventional cast in situ concrete. However, the latest technology reveals various priorities of the precast construction method over the cast in situ concrete. The main aim of this study is to analyze better irrigation lining concrete among two types of casting by conducting visual inspection methods and non-destructive tests to characterize defects. Koga irrigation main canal, which is found in Northwest Ethiopia, was used as a study area because it is made of both in situ and precast concrete linings. The study reveals that the lower strength, severe defects, and lower uniformity due to the high level of difficulty in pouring and vibrating the concrete on the side slopes of the canal were observed in the in situ lined canal. However, the growth of grass in the joints, and sealing of closely spaced and less water-tight joints are observed at the precast part of the canal lining. Providing reinforcement bars on the in situ canals and providing water-tight joints for the precast concrete part are viable solutions.

Will trees or grasses profit from changing rainfall regimes in savannas?

Increasing rainfall variability is widely expected under future climate change scenarios. How will savanna trees and grasses be affected by growing season dry spells and altered seasonality and how tightly coupled are tree-grass phenologies with rainfall? We measured tree and grass responses to growing season dry spells and dry season rainfall. We also tested whether the phenologies of 17 deciduous woody species and the Soil Adjusted Vegetation Index of grasses were related to rainfall between 2019 and 2023. Tree and grass growth was significantly reduced during growing season dry spells. Tree growth was strongly related to growing season soil water potentials and limited to the wet season. Grasses can rapidly recover after growing season dry spells and grass evapotranspiration was significantly related to soil water potentials in both the wet and dry seasons. Tree leaf flushing commenced before the rainfall onset date with little subsequent leaf flushing. Grasses grew when moisture became available regardless of season. Our findings suggest that increased dry spell length and frequency in the growing season may slow down tree growth in some savannas, which together with longer growing seasons may allow grasses an advantage over C3 plants that are advantaged by rising CO2 levels.