Available Water Capacity Research Articles

The Effect of Rainfall and Rain Days On Palm Oil Production

One of the determining factors for water availability for palm oil plants that do not use irrigation systems is rainfall. The availability of water is a major factor that limits the level of production of palm oil plants. The availability of water for oil palm plants in the field is obtained from rainfall data. This research was conducted at PT. Menthobi Makmur Lestari, Lamandau Regency, Central Kalimantan Province, from June 2021 to July 2021. This study uses secondary data analysis including data on of fresh fruit bunches (TBS) production components in the form of components of the number of fruit bunchesg, average fruit bunches weight, number of productive principals, seed fruit bunches weight; data on the production of fres TBS; rainfall data; and monthly rainy day data in 2017, 2018 and 2019 in 6 Divisions. The results of the analysis showed that variable rainfall and rainy days had a real effect on the increase in TBS production at the age of 5 years. Correlation results in plants aged 12, 15 and 18 years with a two-way analysis at the test level of 1% showed the variable rainfall and rainy day had a strong, real and unidirectional relationship. The correlation value of rainfall and consecutive rainy days is 0.892; 0,887; and 0.855 with significance value of 0.000.

The other side of tropical forest drought: do shallow water table regions of Amazonia act as large-scale hydrological refugia from drought?

Tropical forest function is of global significance to climate change responses, and critically determined by water availability patterns. Groundwater is tightly related to soil water through the water table depth (WT), but historically neglected in ecological studies. Shallow WT forests (WT < 5 m) are underrepresented in forest research networks and absent in eddy flux measurements, although they represent c. 50% of the Amazon and are expected to respond differently to global-change-related droughts. We review WT patterns and consequences for plants, emerging results, and advance a conceptual model integrating environment and trait distributions to predict climate change effects. Shallow WT forests have a distinct species composition, with more resource-acquisitive and hydrologically vulnerable trees, shorter canopies and lower biomass than deep WT forests. During 'normal' climatic years, shallow WT forests have higher mortality and lower productivity than deep WT forests, but during moderate droughts mortality is buffered and productivity increases. However, during severe drought, shallow WT forests may be more sensitive due to shallow roots and drought-intolerant traits. Our evidence supports the hypothesis of neglected shallow WT forests being resilient to moderate drought, challenging the prevailing view of widespread negative effects of climate change on Amazonian forests that ignores WT gradients, but predicts they could collapse under very strong droughts.

The potential of fragipans in sustaining pearl millet during drought periods in north-central Namibia

Abstract. Sandy soils with fragipans are usually considered poorly suited for agriculture. However, these soils are cultivated in Namibia as they can secure a minimum harvest during droughts. In order to understand the hydrological influence of fragipans in these soils, Ehenge, their soil moisture content was measured for 4 months. These data were then compared to a deep soil without fragipan, Omutunda, which is more productive during normal years but less productive during droughts. The results illustrate that the combination of sandy topsoil and shallow fragipan has beneficial effects on plant-available water during dry periods. Three reasons can be determined: (i) high infiltration rate in the sandy topsoil, (ii) prevention of deep drainage by the fragipan, and (iii) limitation of evaporation losses through the sand. Consequently, transferring these findings to other dry, sandy areas with fragipans, with respective consequences on farming practices, crop productivity, and food security, should be possible.

Soil water stress and physiological responses of chickpea (Cicer arietinum L.) subject to tillage and irrigation management in lower Gangetic plain

In India, chickpea (Cicer arietinum L.) is mostly cultivated in post-rice residual soil water on marginal lands. Low crop productivity due to terminal water and heat stress during reproductive stages, is a major concern, especially in the rice-fallows of lower Gangetic plains of India. In this backdrop, we examined the effect of different tillage (CT and ZT) and irrigation management (I0 – no irrigation; IF – irrigation at the initiation of the flowering stage; IPF – irrigation at the initiation of pod formation stage, IF+PF – irrigation at both initiation of flowering and pod formation stage) on the performance of chickpea concerning dynamics of soil and crop water stress affecting various physiological characteristics, yield and water productivity (WP) on an Aeric Haplaquept, clay loam soil in rice-fallows of lower Gangetic plain of India during 2017–18 and 2018–19. ZT with standing rice stubbles modified the hydrothermal regime of the soil by lowering the evaporative loss and vertical movement of soil water within the compacted puddled rice soil and significantly altered the stress intensity faced by chickpea at the critical growth stages. On average, 35.0%, 23.5%, and 15.5% higher soil water storage under ZT as compared to CT during vegetative, flowering, and pod formation stages, significantly alters the plant water status as affirmed by higher relative leaf water content, leaf area index, leaf chlorophyll content, stomatal conductance, and transpiration rate and lowering of proline content and canopy temperature. Application of irrigation at the critical growth stages had a positive priming effect on plant water availability under both the tillage practices. Higher yield (1984 kg ha−1), and WP (13.6 kg ha−1mm−1) under ZT-IF treatment combination proved it to be the best, from the perspective of mitigating terminal soil water stress as well as enhancing the productivity of chickpea in the rice-fallows of lower Gangetic plains of India.

Mapping the impact of subsoil constraints on soil available water capacity and potential crop yield

Context The depth-to a constraint determines how much of the soil profile, and the water it contains, can be accessed by plant roots. Information describing the impacts of soil constraints on available water capacity (AWC) and yield is important for farm management, but is rarely considered in a spatial context. Aims and methods The depth-to three yield-limiting constraints (sodicity, salinity, and alkalinity) was mapped across ∼80 000 ha in northern New South Wales, Australia using machine learning and digital soil mapping techniques. Soil AWC was calculated using soil data and pedotransfer functions, and water use efficiency equations were used to determine potential yield loss due to the presence of soil constraints. From this, the most-limiting constraint to yield was mapped. Key results One or more constraints were found to be present across 54% of the study area in the upper 1.2 m of the soil profile, overall reducing the AWC by ∼50 mm and potential yield by an average of 1.1 t/ha for wheat and 0.8 bales/ha for cotton. Sodicity (Exchangeable Sodium Percentage &gt; 15%) was identified as the most-limiting constraint to yield across the study area. Implications The simplification of multiple sources of information into a single decision-making tool could prove valuable to growers and farm managers in managing soil constraints and understanding important interactions with available water and yield.

Hairy vetch role to mitigate crop yield gap in different yield environments at field level

The spatial variability of soil organic matter, plant water availability, and soil nitrogen (N) availability are drivers of crop response to mineral N fertilizer. The complex interaction of these factors is responsible for within-field corn and wheat yield variability. The hairy vetch (HV) cover crop is an economic, environmentally friendly, and efficient N source capable of conciliating crop yield and soil health. Nevertheless, the HV effects to mitigate yield gap of management zone (MZ) have not yet been documented. This study evaluated the effects of HV and mineral N fertilization, in single or combined input, on alleviating crop yield gap. The study was carried out in two croplands southern Brazil. The experimental design was a complete randomized block in a split plot having MZ (high, medium, and low yield) and N fertilizer rates. Wheat and corn N uptake and grain yield had a quadratic adjustment with N fertilizer input, but there was a significant MZ effect, where low yield zone (LYZ) was less responsive. Consequently, mineral N fertilization as a single input to mitigate the yield gap in this MZ was not efficient. On the other hand, HV increased corn N uptake and grain yield mainly in LYZ compared to MYZ and HYZ. HV fully mitigated the yield gap between MYZ and HYZ. The combined use of HV and mineral N fertilization rate adjusted according to N legume credit and MZ was an efficient strategy to boost yield, favoring soil health and environmental protection.

SSR-маркеры, ассоциированные с геном-восстановителем ЦМС 9Е сорго

9E type of cytoplasmic male sterility (CMS) in sorghum belongs to environmentally-regulated types of male sterility in which the restoration of fertility is regulated, along with the genotype, by plant water availability and air humidity on the eve and during the flowering period. For studying the genetic control and understanding the mechanisms of epigenetic processes that regulate the restoration of fertility in this CMS type, the identification of fertility restoring genes (Rf-9E) is extremely important. To solve this problem, we carried out the work on identification of molecular markers associated with the Rf-9E genes. For this purpose, we used the plants of the BC1 population [(9E Pishchevoe 614 × 84/19) × Pishchevoe 614] segregated for fertility restoration. In total, 55 SSR markers were used, mapping all 10 chromosomes of the sorghum genome. It was found that SSR markers located on chromosome 2 of the sorghum genome, sam60498 (23911554…23913675 bp) and sam37585 (33055782…33056867 bp), demonstrate a significant association with the restoration of male fertility in the studied population. In silico analysis of the reference genome of S. bicolor (BTx623) showed that near this region, which includes more than 9 million bp, there are a pericentromeric heterochromatin region, and two PPR genes, 002G142700.1 and 002G144300.1 located at 23465796…23468350 bp and 23810047…23812824bp, respectively. Given that the vast majority of cloned Rf-genes in various plant species, including sorghum, contain sequences of PPR genes, the SSR markers identified in this study can indeed be the molecular markers of 9ECMS fertility-restoring genes. A hypothesis on the relationship between the localization of CMS 9E fertility-restoring genes near heterochromatin and the “moisture-dependent” nature of male fertility restoration in this CMS type is discussed.

Water Productivity of Irrigated Tomatoes in Eastern Canada Based on AquaCrop Simulations

HighlightsMeasured field harvest index improved the performance of AquaCrop simulations.Optimal irrigated tomato yield can be achieved by maintaining available soil water depletion below 25%.Water productivity for tomatoes in humid regions can be suitably simulated using AquaCrop.Irrespective of the soil type, the water productivity was highest for fully irrigated fields compared to water limiting irrigated fields.Abstract. Methodologies to predict crop water requirements in arid and semi-arid regions are well known. Humid regions such as eastern Canada pose a challenge because irrigation is normally only required for short periods during the growing season to supplement rainfall. This study assessed the capability of the AquaCrop model to simulate the effects of different irrigation regimes on field-grown tomatoes (Solanum lycopersicum L.) in the humid region of eastern Canada. The experimental study was conducted at the Horticultural Research station of McGill University, Quebec, Canada. There were three irrigation treatments in 2017 and in 2019, that were based on the % depletion of available water content (AWC). The AquaCrop model was calibrated and verified with the 2017 and 2019 field data, respectively. The verified model was used to predict irrigation water requirements and fruit yield for the driest year (1993) and the average rainfall year (2001) of a 35-year historic weather dataset from 1986 to 2000, for three different soil types (silty clay, sandy loam, and heavy clay) under four irrigation regimes. Model performance was greatly improved when the seasonal harvest index (HI) measured from experimental data was used instead of the default model HI values. AquaCrop was suitable for estimating dry yield and total biomass with RMSE = 0.57 ton ha-1 and 0.89 ton ha-1, respectively, in the calibration phase, and RMSE = 0.28 ton ha-1 and 0.01 ton ha-1 for dry yield and total biomass, respectively, in the verification phase. These results indicate a very high accuracy of AquaCrop to estimate total above ground biomass and fruit yield in humid regions with seasonally adjusted HI values. The predictions showed that maintaining AWC depletion below 25% resulted in no significant decrease in crop yield and biomass, making it an optimum water management guideline for irrigated tomato production in Quebec. The findings of this study are useful to crop growers and water resource managers in eastern Canada, who seek better irrigation strategies to optimize productivity. Keywords: AquaCrop, Crop Modeling, Humid climate, Irrigation water requirement, Tomatoes, Yield.

Mapping of Physical-Water Attributes in an Oxisol Under Sugarcane Cultivation in Ceres Municipality, Goiás State (GO), Brazil

This paper aimed to determine and spatialize physical-hydric attributes in the sugarcane area at the Sugarcane Research Unit in Ceres (GO) in Cerrado (vegetation of the Brazilian interior),. The experiment comprised an area of 285 x 60 m with a 15 m sampling grid, in which a deformed and undisturbed soil sampling was carried out from January 2020 to January 2021. The evaluated attributes were: (a) clay ; (b) sand; (c) silt; (d) soil density (SD); (e) particle density (PD); (f) total porosity (TP); (g) macroporosity (macro); (h) microporosity (micro); (i) water retention in field capacity (FC); (j) water retention in the permanent wilting point (PWP); and (k) total water availability (TWA). All physical attributes showed moderate to strong spatial dependence with adjustments to Gaussian models predominantly for granulometry and exponential, and spherical for the others, ranging from 15.4 to 191.9 m. Results of TWA spatial variability allow defining two management units and show that the soil under study has low water retention in the available water range. This study provides information that enables decision-making in irrigation management and soil decompaction..

Merenje hidrauličkih osobina podloga za uzgoj sa HYPROP sistemom

Knowledge of hydro-physical properties is an essential prerequisite for assessing the suitability and quality of growing media. The method used for sample preparation is important for the measurement results. Three different sample preparation methods were compared. The methods differed in terms of the way the 250°cm3 steel cylinder was filled and the height of preloading. Measurements on loosely filled cylinders were included. The comparison was carried out on 15 growing media using the HYPROP device. HYPROP enables a complex analysis of the hydro-physical properties with high accuracy and reproducibility. The water retention curve, the unsaturated hydraulic conductivity function, the dry bulk density, the shrinkage and the rewetting properties can be measured simultaneously. The air capacity and the amount of plant-available water in pots depend on the height of the pot. In the field, it is related to the field capacity. The quality assessment was carried out both for flowerpots of different height and for field conditions with free drainage. Loosely filled samples consolidated hydraulically shortly after the start of the measurement. These geometric changes can be taken into account with the HYPROP. The sample preparation method - preloading or loose filling - yielded significantly different results for the pore volume, dry bulk density, plant available water and air capacity. The total pore volume of the loosely filled cylinders varied between 86.8 and 95.2°% by vol. (preloaded 81.3 and 87.7°% by vol.). The most critical factor was the air capacity. Loosely filled substrate samples achieved the highest air capacities, but also did not reach the critical value of 10°% by volume in shallow flowerpots, e.g. in 10 cm pots with 5.8°% by volume. The sample preparation method, measurement and quality assessment of the hydro-physical properties of growing media should be adapted to the conditions of use - whether they are used in a field with free drainage or in pots or containers in greenhouses.

Plantation tree growth responses to P, N, K and minor and trace elements on low fertility savanna soils

Context Widespread soil nutrient limitations in savanna soils typically constrain plantation tree growth, and hence limit economic opportunities in tropical regions. Fertilisation offers an approach to overcome soil nutrient limitations, but requires research on nutrient contents and rates to maximise plant growth while avoiding nutrient imbalances that have stunted plant growth under some fertiliser regimes. Aims To test the hypothesis that multiple nutrient limitations exist in savanna soils, with nutrient deficiencies exposed in sequence with fertiliser addition. Methods Factorial field experiments tested the growth of the plantation timber species African mahogany (Khaya senegalensis) to applications of phosphorus, potassium, nitrogen and minor and trace elements (referred to as the T treatment) on a kandosol soil near Darwin, Australia. Key results Under high stocking rates to induce deficiencies sooner through utilisation of a high proportion of the available nutrient capital, positive responses and interactions to all four main treatments were recorded. There were step-wise responses to phosphorus, potassium, nitrogen and the T treatment. Treatments with greater mean tree growth were more uniform than lesser-growing treatments, even though the largest and smallest individuals were similar across treatments. Conclusions Consistent with our hypothesis, correcting one soil nutrient deficiency exposed another in sequence as nutrient reserves were depleted in a drying soil. Variation in tree performance across plots indicates that testing of soil nutrients and fertiliser responses need to be assessed in replicate and dispersed samples. Implications Khaya senegalensis demonstrated potential for plantation use in northern Australia with minimal mortality from termites and other causes, if supported with broad-spectrum fertilisation balanced to match plant growth and water availability.

THE SHORT TERM EFFECT OF TILLAGE SYSTEM ON SOIL MOISTURE RETENTION IN BAYELSA STATE, NIGERIA

The objective of the study was to determine the short time effect of tillage system on the water retention capacity of soils in the Niger Delta University Teaching and Research Farm, Bayelsa State. Five treatments (No-till, Digging, Hoeing, Hoeing+Digging once, and Hoeing+Digging twice) were considered. Plant Available Water Content (PAWC) and the Soil Water Holding Capacity (SWHC) were used to determine the soil water retention capacity. The results revealed that the crude tillage methods had a significant (P&lt;0.05) impact on some soil properties. The highest bulk density (1.18g/cm3) was found in the No-till zone, while the lowest (0.89g/cm3) was in the Hoe+Digging twice method. The tillage methods also affected the hydraulic conductivity as the highest value (4.67cm/hr) was found in the hoe+digging zone and the lowest (2.61cm/hr) in the no-till area. Furthermore, the PAWC and SWHC were highest (0.14cm3cm-3 and 2.03cm) at the No-till zone and lowest (0.06 cm3cm-3 and 0.95cm) at the Hoe+Digging twice zone. It is therefore recommended that, for unrestricted flow of water through the soils, compacted soils should be pulverized using tillage implements. Also, for optimal plant water availability, there should be less tillage on coarse-textured soils, as the disturbance promotes rapid leaching.

Synergy of remotely sensed data in spatiotemporal dynamic modeling of the crop and cover management factor

Soil erosion is a threat to the water quality constituents of sediments and nutrients and can cause long-term environmental damages. One important parameter to quantify the risk of soil loss from erosion is the crop and cover management factor (C-factor), which represents how cropping and management practices affect the rates and potential risk of soil erosion. We developed remotely sensed data-driven models for dynamic predictions of C-factor by implementing dynamic land cover modeling using the SWAT (Soil and Water Assessment Tool) model on a watershed scale. The remotely sensed processed variables included the enhanced vegetation index (EVI), the fraction of photosynthetically active radiation absorbed by green vegetation (FPAR), leaf area index (LAI), soil available water content (AWC), slope gradient (SG), and ratio of area (AR) of every hydrologic response unit (HRU) to that of the total watershed, comprising unique land cover, soil type, and slope gradient characteristics within the Fish River catchment in Alabama, USA between 2001 and 2014. Linear regressions, spatial trend analysis, correlation matrices, forward stepwise multivariable regression (FSMR), and 2-fold cross-validation were conducted to evaluate whether there were possible associations between the C-factor and EVI with the successive addition of remotely sensed environmental factors. Based on the data analysis and modeling, we found a significant association between the C-factor and EVI with the synergy of the environmental factors FPAR, LAI, AWC, AR, and SG (predicted R 2 ( R 2 pred ) = 0.51; R 2 = 0.68, n = 3 220, P < 0.15). The results showed that the developed FSMR model constituting the non-conventional factors AWC ( R 2 pred = 0.32; R 2 = 0.48, n = 3 220, P < 0.05) and FPAR ( R 2 pred = 0.13; R 2 = 0.28, n = 3 220, P = 0.31) was an improved fit for the watershed C-factor. In conclusion, the union of dynamic variables related to vegetation (EVI, FPAR, and LAI), soil (AWC), and topography (AR and SG) can be utilized for spatiotemporal C-factor estimation and to monitor watershed erosion.

Biochar Amended Soils and Water Systems: Investigation of Physical and Structural Properties

There are significant regional differences in the perception of the problems posed by global warming, water/food availability and waste treatment recycling procedures. The study illustrates the effect of application of a biochar (BC) from forest biomass waste, at a selected application rate, on water retention, plant available water (PAW), and structural properties of differently standard textured soils, classified as loamy sand, loam and clay. The results showed that soil water retention, PAW, and aggregate stability were significantly improved by BC application in the loamy sand, confirming that application of BC to this soil was certainly beneficial and increased the amount of macropores, storage pores and residual pores. In the loam, BC partially improved water retention, increasing macroporosity, but decreased the amount of micropores and improved aggregate stability and did not significantly increase the amount of PAW. In the clay, the amount of PAW was increased by BC, but water retention and aggregate stability were not improved by BC amendment. Results of the BET analysis indicated that the specific surface area (BET-SSA) increased in the three soils after BC application, showing a tendency of the BET-SSA to increase at increasing PAW. The results obtained indicated that the effects of BC application on the physical and structural properties of the three considered soils were different depending on the different soil textures with a BET-SSA increase of 950%, 489%, 156% for loamy sand, loam and clay soil respectively. The importance of analysing the effects of BC on soil water retention and PAW in terms of volumetric water contents, and not only in terms of gravimetric values, was also evidenced.

The influence of depth on the water retention properties of vineyard soils

The relationships between the factors that influence the water retention properties of soils (bulk density, sand, silt, clay, organic matter and CaCO3 contents), and their gravimetric moisture at field capacity (FC), permanent wilting point (PWP), and their available water capacity (AWC), were studied in 104 surface horizons and 95 subsurface horizons of vineyard soils in the Castilla-La Mancha region of Spain. Taking all soil types together, the depth of the horizon was found to influence PWP and AWC, while the factors with the most significant linear relationship with AWC, both for surface and subsurface horizons, were sand content (r = − 0.47 and − 0.63, respectively) and silt content (r = 0.37 and 0.62, respectively). However, when each FAO Reference Soil Group was studied independently, only Calcisols, Luvisols and Regosols showed significant differences between these horizons in terms of AWC. Greater clay contents were associated with greater FC, PWP and AWC only in Luvisol surface horizons (r = 0.44, 0.40 and 0.33, respectively), and with FC and PWP in subsurface horizons (r = 0.64 and 0.64). A greater CaCO3 content was associated with a greater AWC only in Calcisols, both in surface and subsurface horizons (r = 0.49 for both). Finally, the organic matter content and bulk density of the different soil types showed no clear trend with respect to any soil water retention property; a certain positive effect of organic matter on water retention properties was observed only in the surface horizon and not in the subsurface horizon. A map of the spatial distribution of AWC in surface and subsurface horizons is proposed as a soil management instrument.

Impact of in-field soil heterogeneity on biomass and yield of winter triticale in an intensively cropped hummocky landscape under temperate climate conditions

Crop cultivation provides ecosystem services on increasingly large fields. However, the effects of in-field spatial heterogeneity on crop yields, in particular triticale, have rarely been considered. The study assess the effects of in-field soil heterogeneity and elevation on triticale grown in an intensively cropped hummocky landscape. The field was classified into three soil classes: C1, C2, and C3, based on soil texture and available water capacity (AWC), which had high, moderate, and low yield potential, respectively. Three elevations (downslope (DS), midslope (MS), and upslope (US)) were considered as the second study factor. An unbalanced experimental design was adopted with a factorial analysis of variance for data analysis. Temporal growth analysis showed that soil classes and elevation had significant effects. Generally, better growth was observed in C1 compared to that of C3. DS had a lower yield potential than that of MS and US. In addition, the interactive effect was confirmed, as triticale had poor growth and yield in C3 on the DS, but not on US. Crop physiological parameters also confirmed the differences between soil classes and elevation. Similarly, soil moisture (SM) content in the plow layer measured at different points in time and AWC over the soil profile had a positive association with growth and yield. The results confirmed that spatial differences in AWC and SM can explain spatial variability in growth and yield. The mapping approach combining soil auguring techniques with a digital elevation model could be used to subdivide fields in hummocky landscapes for determining sub-field input intensities to guide precision farming.

One-time omission of puddling improves soil structure and post-rice soybean yield in clay-rich fields within paddy–soybean rotation systems in central Hokkaido, Japan

A one-time omission of puddling was noted to increase post-rice soybean yields within the paddy–soybean rotation systems in central Hokkaido, Japan. We analyzed the physical, chemical, and biological properties of soil via an onsite survey in 47 farmers’ soybean fields where either puddled transplanted rice (PT), nonpuddled transplanted rice (NT), or dry direct-seeded rice (DS) was cultivated in the previous year (referred to as one-time PT, NT, and DS treatments, respectively). The objective of the study was to determine the key soil parameters that could explain the higher post-rice soybean yield following the one-time omission of puddling (NT and DS treatments). In addition, soybean yield and soil properties were surveyed in an experimental field experiment where PT and NT treatments were applied for 3 consecutive years with the expectation that the increases in post-rice soybean yield caused by the omission of puddling (NT treatment) would be more pronounced. In the survey of farmers’ field, soybean yields were comparable among the one-time PT, NT, and DS treatments when the clay content was < 40%. However, soybean yield decreased as the clay content increased only under the one-time PT treatment. The adverse effects of puddling (PT treatment) on clay-rich soil appeared in a few soil physical parameters but not on any soil chemical and biological parameters. In the 34 selected clay-rich farmers’ fields (clay content >40%), narrow macropore and mesopore volumes, which indicate total available water capacity, were significantly (P < 0.05) lower under the one-time PT treatment than under the other two treatments. At the same time, the narrow macropore volume was significantly (P < 0.05) correlated with soybean yield. The one-time omission of puddling (NT and DS treatments) adopted in the surveyed farmers’ fields did not affect the wide macropore volume. Three consecutive years of NT treatment improved several soil physical properties as well as soybean root development in the experimental field. However, these improvements did not significantly increase soybean yield in the experimental field where the clay content was < 40%. These findings suggest that the one-time omission of puddling (NT and DS treatments) prevents the decreasing in the yields of post-rice soybean in clay-rich soils in central Hokkaido. The stable soybean yield, irrespective of the clay content, after the one-time omission of puddling (NT and DS treatments) in fields was attributed to the increased plant-available water capacity owing to the increased narrow macropore and mesopore volumes without clear changes in the wide macropore volume. By contrast, the effects of the one-time and three-time omission of puddling (NT and DS treatments) were not obvious in non–clay-rich field conditions in central Hokkaido.

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.

Leaf trait modification in European beech trees in response to climatic and edaphic drought.

Leaf morphological and physiological traits control the carbon and water relations of mature trees and are determinants of drought tolerance, but it is not well understood how they are modified in response to water deficits. We analysed five sun-canopy leaf traits (mean leaf size (LS), specific leaf area (SLA), Huber value (HV), water potential at turgor loss point (Ψtlp ) and foliar carbon isotope signature (δ13 C)) in European beech (Fagus sylvatica L.) across three precipitation gradients sampled in moist (2010), dry (2019) and very dry (2018) summers, and tested their response to short-term water deficits (climatic water balance (CWB) preceding sample collection) and long-term water availability (mean annual precipitation (MAP), plant-available soil water capacity (AWC) and neighbourhood competition). Across the 34 sites, LS varied seven-fold (3.9-27.0 cm2 ), SLA four-fold (77.1-306.9 cm²·g-1 ) and HV six-fold (1.0-6.65 cm2 ·m-2 ). In the 2018 dataset, LS showed a negative and HV a positive relationship to MAP, which contradicts relations found in multi-species samples. Average Ψtlp ranged from -1.90 to -2.62 MPa and decreased across the sites with decreasing CWB in the month prior to measurement, as well as with decreasing MAP and AWC in 2019. Studied leaf traits varied considerably between years, suggesting that mast fruiting and the severe 2018 drought caused the formation of smaller leaves. We conclude that sun-canopy leaf traits of European beech exhibit considerable plasticity in response to climatic and edaphic aridity, and that osmotic adjustment may be an important element in the drought response strategy of this anisohydric tree species.

Techno-economic analysis reveals the untapped potential of wood biochar

The United Nations estimates the rate of deforestation over 10 million hectares per year, with additional infested wood available due to drought, bark beetle calamity and other damage vectors. Processing the hard-to-reach infested wood into biochar via mobile pyrolysis units seems to be a good option for fire prevention. However, since most biochar is currently produced mainly from biological waste, there is not enough experience with wood biochar on a large scale. Review of current knowledge, followed by techno-economic assessment reveals that following the chemical composition of the feedstock, wood biochar outperforms other types of biochar in terms of high porosity. Therefore, wood biochar shows excellent results in increasing the amount of plant-available water content in soil and appears to be an excellent tool for recycling nutrients (especially into plant-available forms of phosphorus and nitrogen). The overall positive effects of biochar application change from abiotic to biotic over time because as it decays, many of its physical properties disappear, but it can boost soil microbial communities on which soil fertility depends. As global climate change creates a wide range of factors that damage forest cover, wood biochar consequently represents untapped potential in the field of soil, nutrient, and energy management.