Long-term Soil Productivity Research Articles

Innovative Soil Management, Soil Amendments and Soil Conservation Strategies for Boosting Horticultural Crops Yields

Innovative soil management, soil amendments, and soil conservation strategies are pivotal in boosting horticultural crop yields. By integrating cutting-edge techniques, such as precision agriculture and organic amendments, these approaches optimize soil health and fertility, enhancing plant growth and productivity. Soil amendments, including biochar, compost, and green manures, improve soil structure, water retention, and nutrient availability, creating a favourable environment for horticultural crops. Additionally, soil conservation practices like cover cropping, contour ploughing, and agroforestry prevent erosion, maintain soil organic matter, and promote biodiversity. These strategies collectively contribute to sustainable agriculture, ensuring higher yields and long-term soil productivity while mitigating environmental impacts. Through a holistic approach to soil management, horticulturists can achieve robust crop performance and resilience against climatic challenges.

Enhancing Soil Health and Fertility Management for Sustainable Agriculture: A Review

In modern agriculture, ensuring soil health and effective fertility management are paramount for sustainable crop production and environmental stewardship. This review article comprehensively explores a spectrum of strategies aimed at enhancing soil health and fertility management within the context of sustainable agriculture. Beginning with an overview of the pivotal role soil health plays in agricultural systems, the review meticulously examines the significance of adopting sound soil fertility management practices to sustain soil productivity while mitigating adverse environmental impacts. Traditional and innovative approaches to soil management are thoroughly discussed, encompassing a range of practices such as organic amendments, cover cropping, crop rotation, reduced tillage, and integrated nutrient management. These practices, deeply rooted in agricultural traditions, are shown to enhance soil structure, foster nutrient cycling, and promote beneficial soil microbial communities, thereby contributing to long-term soil health and productivity. Furthermore, the review elucidates emerging technologies and methodologies that hold promise for revolutionizing soil health and fertility management in sustainable farming systems. Precision agriculture techniques leveraging GPS, remote sensing, and data analytics are highlighted for their potential to optimize resource use and improve crop management practices. Biochar application, a burgeoning area of research, is explored for its ability to enhance soil fertility, sequester carbon, and improve soil water retention. Additionally, manipulation of the soil microbiome through innovative techniques presents exciting opportunities for enhancing soil health and resilience, the review underscores the importance of continued research, education, and policy support in promoting sustainable soil management practices. Recommendations for future research directions are provided, emphasizing the need for interdisciplinary collaborations, long-term field studies, and farmer participatory research. Practical implications for farmers and policymakers are also delineated, emphasizing the imperative of adopting holistic approaches to soil management that integrate traditional wisdom with cutting-edge technologies. By embracing sustainable soil management practices, farmers and policymakers can safeguard soil health, enhance agricultural productivity, and ensure the long-term sustainability of our food systems and environment.

Evaluating nutrient balances, soil carbon trends, and management options to support long-term soil productivity in smallholder crop-livestock systems

Evaluating nutrient balances, soil carbon trends, and management options to support long-term soil productivity in smallholder crop-livestock systems

Soil disturbance, amelioration and rehabilitation affect forest growth, health, soil carbon and chemistry on five long-term soil productivity (LTSP) sites in southeastern British Columbia

Soil disturbance amelioration affected tree survival, growth, health, mineral soil chemistry, and their covariation on five Long-Term Soil Productivity (LTSP) sites in southeastern British Columbia. The two most different LTSP treatments (baseline disturbance of no compaction / all organic matter left, versus most severe of heavy compaction / forest floor removed) were compared to five amelioration treatments: rehabilitation of most severe LTSP treatment (soil tillage with or without incorporation of removed forest floor [Rehab + FF]), root disease (Armillaria ostoyae (Romagn.) Herink) amelioration treatments (stump removal or biological with Hypholoma fasiculare), and enhancement of soil organic matter (tilling extra forest floor into mineral soil). Treatment significantly (p < 0.05) affected 10-year mineral soil carbon, nitrogen, sulfur, mineralizable nitrogen, and potassium, which were lower on forest floor removal treatments and higher on forest floor addition treatments (27 to 97% of baseline versus 78 to 183% of baseline, respectively). Western white pine (Pinus monticola Dougl. ex D.Don) 15-year productivity (m3/ha) was significantly affected by treatment (Rehab + FF yielding a 10 fold increase in productivity versus the poorly growing baseline treatment), with treatment also significant when total disease was a covariate and for average and total volume when mineral soil Ca:Al ratio was a marginally significant (p < 0.1) covariate, and for survival when the incidence of total disease or white pine blister rust (Cronartium ribicola) were significant covariates; or with mineral soil C:N ratio as a significant covariate. The incidence of blister rust and total disease were significantly influenced by treatment when C:N was a significant covariate. For 20-year lodgepole pine (Pinus contorta Dougl. Ex Loud) there were no direct relationships apparent, but western gall rust (Endocronartium harknessii) had treatment significant when total sulfur was a significant covariate. Fifteen- and twenty-year Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) had no significant relationships. Results demonstrate that restoring or adding extra organic matter (forest floor) into mineral soil increased soil carbon and related nutrients and can increase above ground carbon (forest productivity). Conversely, removing forest floor lowered mineral soil carbon and generally lowered tree volume. Varied effects due to growth limiting factors like frost and competing vegetation affected results on a few plots. Recommendations include leaving or enhancing organic matter onsite for soil carbon, nutrients, forest health and site productivity. Further analysis with the larger LTSP dataset and ongoing monitoring is encouraged to determine if the results persist in the long-term and to better understand the significant covariate relationships.

Evaluation of Physico-chemical Parameters of Soil in Different Cropping Systems and their Co-relation with Earthworm Diversity

Aim: The present study is an attempt to evaluate the impact of earthworm diversity on physico-chemical parameters of soil in different cropping systems (i.e. basmati-wheat, basmati-chickpea, soybean-wheat, moong-wheat) under organic and conventional farming systems.&#x0D; Place and Duration of Study: The study was conducted at the School of Organic Farming, Punjab Agricultural University, Ludhiana, Punjab, India from June, 2020 to March 2021.&#x0D; Methodology: The four earthworm species found during the study period are Metaphire posthuma, Lampito mauritti, Amynthas morissia and Travoscolides chengannure, which belong to two families i.e. Megascolicidae and Octochateidae. Out of these Travoscolides chengannure was reported for the first time in Punjab.&#x0D; Results: The results indicate that richer earthworm diversity was found in the organic farming systems as compared to the conventional farming systems. The correlation analysis of earthworm abundance with the physicochemical parameters of soil in different farming systems revealed that the abundance of earthworms in organic farming system shows positive but non-significant correlation with pH, nitrogen and potassium levels. In conventional farming system, significant positive correlation (p=0.01) was found for organic carbon, electric conductivity and nitrogen.&#x0D; Conclusion: The findings of this encourage switching from conventional to organic farming practices. These practices not only increase earthworm diversity, but enrich the soil with many major and micro-nutrients. The agriculture practices which are earthworm-friendly should be adopted for long-term soil productivity.

Wildfire loss of forest soil C and N: Do pre-fire treatments make a difference?

Losses of C and N from the forest floor and top 20-cm of soil were estimated following separate severe wildfires at two Long-Term Soil Productivity sites in the Sierra Nevada of California, USA. Experimental treatments applied 20 years prior to the wildfires included factorial combinations of 1) organic matter (OM) removal following clear-cut harvesting (SO, stem only harvest, WTH, whole-tree harvest, and WTH + FF, WTH plus the forest floor removal), 2) soil compaction (three levels of intensity), and 3) with and without understory vegetation control. Wildfires caused complete losses of the forest floor in all treatments and also oxidized varying portions of OM in the topsoil. As such, pre-fire forest floor measures were used as an estimate of forest floor C and N loss, and post-fire soil measures of C and N were compared to pre-fire soil data to estimate of mineral soil losses. Averaged over all treatments, the less-productive site that also had lesser accumulations of detritus (Wallace) lost 35.1 Mg C ha−1, or 25 % of its original C stores, while the more-productive site with greater detritus (Rogers) lost 18.4 Mg C ha−1, or 20 % of its original. The SO treatments that left harvest residue on site ended up with much greater losses of C: 36 % versus 15 and 17 % for WTH and WTH + FF, respectively. The SO also yielded the largest losses (25–30 %) of C in the top 10-cm of soil. The other treatments had smaller or inconsistent effects (understory vegetation control) or no effect (soil compaction). Our results suggest that potential benefits from SO by leaving residue on site to soil C and N accumulation can also be readily eliminated by wildfire which commonly occurs at these fire-prone forest ecosystems.

Delineation and Mapping of Groundwater Quality in Chengalpattu District of Tamil Nadu, India

Groundwater is a major natural source of water supply all around the world. It's utilised for irrigation, industry, and even household purposes. The quality of groundwater is important for irrigation. Irrigation water quality plays a critical role in long-term soil productivity. To assess the quality of the groundwater, 149 samples were taken in May 2022 from the coastal blocks of the Chengalpattu district: Chithamur (42), Lathur (37), Thirukalukundram (31), and Thiruporur (39). The samples were analysed in accordance with the appropriate protocol. The study revealed that the coastline blocks pH ranges from 8.92 to 7.52 and their EC ranges from 11.50 to 0.13 dS m-1. The Sodium Absorption Ratio (SAR) ranges from 20.00 to -6.80, while the Residual Sodium Carbonate (RSC) ranges from 14.77 to 0.26 meq/L. The Chengalpattu district has a high concentration of alkali water, according to CSSRI, Karnal classification. Among the coastal blocks, the Thiruporur block contains more alkali water compared to other coastal blocks (46%).

Green manure for agricultural sustainability and improvement of soil fertility

Many farmers are incorporating green manuring into their practices as a result of the growing issues facing agriculture, such as climate change, extreme weather events, soil deterioration, and land contamination due to the excessive use of chemical fertilizers. Growing green manure is a useful and affordable way to ensure the long-term productivity of agricultural soils. Given the significant loss of soil fertility caused by improper agronomic practices, human-induced land degradation is extremely serious. Due to their positive effects on the physical, chemical, and biological quality of the soil as well as the proper justification of soil fertility, green manures can play a significant role. Utilizing green manure is one of the trends in environmental protection that aids in the agricultural sector's transition to sustainability by conserving resources and meeting consumer demand for food. Modern farmers are faced with a number of challenges as they try to transition to productive and ecologically friendly practices. To preserve soil fertility while utilizing less chemicals is one of them. Green manure crops could be a potential answer to this issue. Back in ancient times, farmers learned that this method had a positive effect on the soil. Thus, for growers who want to reduce the use of hazardous chemicals for soil fertilization, green manure is indispensable. In terms of operations, many farmers must employ green manure to reduce the overuse of chemical fertilizers in agriculture.

Review Effect of Combined Application of Organic and Inorganic Fertilizer on Cabbage and Its Economic Importance’s

Cabbage belongs to the family cruciferae. Among the other vegetable cabbage is one of the easiest crops to establish and most of the people grow this crop in their home garden. In the major vegetable-growing areas, it is also an essential economical and rotational crop. Cabbage is an important vegetable crop and it is one of favorite crop grown in kitchen garden because easy to rise. Cabbage is high in vitamins A, C, K, B 1 , B 2 , B 6 , calcium, dietary fiber, and protein whether eaten fresh in salads or boiled or cooked in stews and soups. Cabbage is commonly consumed as a cooked or stir-fried vegetable, or as a raw element in salads such as coleslaw and mixed salads. Cabbage growth and yield are known to be influenced by a variety of cultural practices and growing settings. Nutrition is a major determinant of cabbage growth and production. Production of cabbage could be enhanced through efficient use of applied both organic and inorganic fertilizer. When compared to chemical fertilizers, organic fertilizers (cow dung, poultry manure, and vermin-compost) resulted in better nutrient uptake. Due to decreasing soil fertility, vegetable crop yields decreased. Organic manure can help to keep soil fertility and crop production in check. It is true that the use of inorganic fertilizers for crops has a negative impact on soil health, but organic fertilizers do not have this issue. Neither chemical fertilizers nor organic manure can help achieve long-term crop yield on their own. Because of deterioration in soil physical, chemical, and biological qualities, high yield levels could not be sustained using simply balanced chemical fertilizers over time. Integrated nutrient management is the most effective method for ensuring long-term soil fertility and productivity of cabbage. The objective of this review is to review the effect of combined application of organic and inorganic fertilizer on cabbage and its economic importance’s. Keywords: cabbage, organic, inorganic, combined, fertilizer DOI: 10.7176/JBAH/11-19-02 Publication date: October 31 st 2021

Global Assessment of Agricultural Productivity Losses from Soil Compaction and Water Erosion.

To guide us toward a sustainable future, the impacts of human activities on natural resources need to be understood and quantified. In this study on global agriculture, we use a Life Cycle Assessment framework to estimate potential long-term soil productivity losses caused by soil compaction and water erosion due to agricultural crop production. We combine several data sets to model spatially resolved Life Cycle Inventory information at the global level and multiply results with characterization factors from a previous publication. The global picture shows a compaction-stressed "Global North" and an erosion-stressed "Global South", with some countries and regions in between, for example, China and parts of South America. Results show that both compaction and water erosion impacts matter at the global level and that overall potential long-term productivity losses of 10-20% can be expected, with high relative impacts on low input production systems. These losses might limit long-term agricultural productivity and lead to additional land use change. Our work adds to and extends the discussion of global assessments of soil degradation. Furthermore, we prove the suggested framework to be applicable and useful for Life Cycle Assessments and other studies and provide results that can be used in such global assessments.

Fifteen-year tree growth on standard long-term soil productivity trials and various adjacent amelioration treatments at Interior Cedar-Hemlock sites in southeastern British Columbia and northern Idaho

Understanding the relationship between soil disturbance and tree growth is key to sustainable forest management. We report fifteen-year tree growth results of Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) and western white pine (Pinus monticola Dougl. ex D.Don) growth following clearcut harvesting and installation of three replicates of the international Long-Term Soil Productivity (LTSP) trial protocols. Additional amelioration plots were also established on each replicate site to study rehabilitation of the most severe disturbance, treatment of Armillaria root disease, and enhancement of soil organic matter. Stark differences were found among the various treatments and species. Vegetation control resulted in significantly better growth for both tree species across the core LTSP treatments and amelioration treatments. On the core LTSP treatments, organic matter removal had a significant negative effect on Douglas-fir growth. Amelioration treatments resulted in similar survival and similar or better volume growth than the core LTSP treatments, with the exception of poor volume growth after compaction rehabilitation with no organic matter returned into the soil. Compaction significantly influenced Douglas-fir survival and was often higher on moderate compaction plots. On some sites there was decreased survival and growth associated with heavy compaction that will likely influence longer-term outcomes with a more variable and changing climate. Overall, results to date on the core LTSP treatments, amelioration treatments, and adjacent miniplots reported elsewhere suggest that forest floor removal causes negative growth and, combined with severe compaction, caused both negative growth and poor survival. In the Interior Northwest it is still prudent to minimize soil disturbance and leave organic matter onsite unless there is site specific evidence to the contrary. Additional work is required to reap the full, long-term benefit of the installations. Recommendations are provided highlighting the critical work that should be completed in the near future before biological evidence is lost to decay, including suggestions for further data analysis and extension, the need to continue LTSP core, amelioration and miniplot measurements to demonstrate and calibrate sustainable forest resource management. Our data suggest considering changes to current soil disturbance policy and forest operations based on the current results regarding forest floor displacement.

Assessing temporal response to biomass removal: A framework for investigating evolving constraints on boreal stand development

Impacts of harvest intensity and soil disturbance on site productivity are likely to vary with stand development stage and interactive processes related to ecosystem function. On upland boreal sites, stand productivity may initially be constrained by microclimatic conditions. However, increasing nutrient demands and overstory light interception associated with canopy development may place progressively greater emphasis on nutrient availability, profile water storage capacity and asymmetric competition. We illustrate these effects using 20-yr post-harvest data from fourteen jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) BSP) Long-term Soil Productivity (LTSP) installations in northern Ontario.Initial growth and ten-year survival were as great or greater without forest floors (NFF), but by year 15 dominant height increments were usually greater with intact forest floors (FF). Growing season frost occurrence and high vapor pressure deficits occurred more frequently with FF than NFF treatments during the initial stand establishment phase. Similarly, mean growing season soil temperatures were 2-5˚C warmer with NFF during this phase, with stand Leaf Area Index (LAI) values < 0.5. During the following Accelerated Growth phase, treatment differences in microclimate dissipated as LAI increased. Foliar N concentrations and N:P ratios, and soil net N mineralization were usually greater from an early age with FF, and often declined as canopy closure approached. Likewise, modelled site-level constraints related to soil water availability increased with stand development, peaking at LAI values associated with the stem exclusion stage. Placing post-harvest response (i.e., impacts of harvest intensity) in the context of relationships among stand structural development, changes in microclimate, and resource supply and demand should provide greater insights into longer-term effects of establishment practices.

The Long-Term soil productivity study after three decades

The Long-Term soil productivity study after three decades

Positive but variable effects of crop diversification on biodiversity and ecosystem services.

Ecological theory suggests that biodiversity has a positive and stabilizing effect on the delivery of ecosystem services. Yet, the impacts of increasing the diversity of cultivated crop species or varieties in agroecosystems are still under scrutiny. The available empirical evidence is scattered in scope, agronomic and geographic contexts, and impacts on ecosystem services may depend on the type of diversification strategy used. To robustly assess the effects of crop diversification in agroecosystems, we compiled the results of 95meta-analyses integrating 5156 experiments conducted over 84 experimental years and representing more than 54,500 paired observations on 120 crop species in 85 countries. Overall, our synthesis of experimental data from across the globe shows that crop diversification enhances not only crop production (median effect +14%) but also the associated biodiversity (+24%, i.e., the biodiversity of non-cultivated plants and animals), and several supporting and regulating ecosystem services including water quality (+51%), pest and disease control (+63%) and soil quality (+11%). However, there was substantial variability in the results for each individual ecosystem service between different diversification strategies such as agroforestry, intercropping, cover crops, crop rotation or variety mixtures. Agroforestry is particularly effective in delivering multiple ecosystem services, that is, water regulation and quality, pest and diseases regulation, associated biodiversity, long-term soil productivity and quality. Variety mixtures, instead, provide the lowest benefits, whereas the other strategies show intermediate results. Our results highlight that while increasing the diversity of cultivated crop species or varieties in agroecosystems represents a very promising strategy for more sustainable land management, contributing to enhanced yields, enhanced biodiversity and ecosystem services, some crop diversification strategies are more effective than others in supporting key ecosystem services.

Effects of harvesting intensity, vegetation control and fertilization on 5–20 year post-harvest N availability in boreal jack pine and black spruce forest soils in northern Ontario, Canada

The impact of harvesting intensity, vegetation control and fertilization on soil N availability 5–20 years post-harvest was determined at 18 jack pine and black spruce forests in northern Ontario, Canada. The study sites are affiliated with the North American long-term soil productivity (LTSP) study. Boreal forest growth is commonly N limited and young stands approaching crown closure acquire most of their N from the soil. The study sites represented a range of soil types and were harvested with three levels of organic matter removal (stem-only harvest, full-tree harvest and full-tree harvest with organic horizon removal by blading). Three study sites had multiple applications of glyphosate to control competing vegetation and one site included a trial with two applications of N, P, K fertilizer to the full-tree harvest treatment. We used short-term anaerobic laboratory incubations and in-situ closed top tube growing season incubations to determine mineralizable N and net N mineralization, respectively. Profile (organic plus mineral horizons) mineralizable N pools were higher in operational clearcut (stem-only and full-tree harvesting) treatments compared to the uncut reference forest 10–14 years post harvest. Full-tree harvesting with blading significantly reduced profile mineralizable N pools at this time compared to operational harvesting, while the same treatment at one upland site also reduced net N mineralization pools. Profile mineralizable N pools and microbial biomass C and N were lower in full-tree compared to stem-only harvesting treatments, suggesting that increased slash retention with stem-only harvesting was playing a role in enhanced soil N availability at a time when plantations were approaching a period of greater N demand. Fertilization and vegetation control treatments had few effects on N indices, although net N mineralization pools for the stem-only and full-tree harvest that also had the repeated herbicide treatment were consistently, but not significantly, lower than non-herbicided treatments. Soil N indices were useful predictors of dominant height growth for jack pine to a greater degree than for black spruce, and soil N concentrations were as effective at predicting height growth as more resource intensive measurements. Our results point to the importance of continued monitoring of soil and stand conditions at these LTSP sites as treatment effects on soil N cycling and site productivity will likely continue to evolve. At this stage of stand development, full-tree harvesting plus organic horizon removal, followed by operational harvesting has led to lower soil N availability than operational tree-length harvesting, and stands with understory vegetation control are now showing indications of reduced N availability.

Wood stake decomposition twenty years after organic matter removal at the Lake States LTSP sites

Organic matter (OM) is an integral part of site productivity for a forest, and understanding the effects of OM removal on various forms of carbon (C) cycling is important for land managers and for policy makers. In this study, we utilized the Lake States Long-Term Soil Productivity (LTSP) study sites, located along a gradient in soil texture (clay, silt loam and sand) and high to low productivity, to evaluate the impacts of two OM removal treatments on belowground wood decomposition. In 2013, approximately 20 years after the LTSP treatments had been installed, we placed standardized aspen and loblolly pine wood stakes in the mineral soil of plots receiving the bole only harvesting treatment (BO) and the whole tree harvesting with forest floor removal treatment (WT + FF), and in plots in an adjacent unharvested reference area (1350 wood stakes total). Soil was also sampled to characterize the microbial community composition in the various treatments. From 2014 to 2018, wood stakes were removed from each treatment, and mass loss determined. We found significant differences in wood stake decomposition among the three sites, and between the two wood species, but little impact of timber harvesting and surface OM removals on decomposition. Soil microbial composition also reflected site differences in stake decomposition. We conclude that clearcut harvest and surface OM removal had little effect on stake mass loss in the mineral soil 20 years after the treatments were initiated, and the inherent soil factors are now controlling decomposition.

Long-term effects of organic matter removal, compaction, and vegetation control on tree survival and growth in coarse-textured, low-productivity soils

The Long-Term Soil Productivity Network is providing a systematic examination of the effects of organic matter removal and compaction on a variety of different soils and forest types across North America. Here we report on the 22nd-year survival and height growth of white oak (Quercus alba), northern red oak (Q. rubra), and shortleaf pine (Pinus echinata) on rocky, nutrient-poor soils that have a low to moderate water holding capacity in the Missouri Ozark Highlands. Treatments included three levels of organic matter removal (sawlog, whole tree, and whole-tree plus forest floor) and three levels of soil compaction (none: bulk density = 1.34 g cm−3; moderate: bulk density = 1.65 g cm−3; and severe: bulk density = 1.78 g cm−3) each with and without vegetation control. Following treatments, bareroot, 1–0 white oak, northern red oak, and shortleaf pine seedlings were planted at a 3:3:1 ratio, approximating the distribution of these species in this region. Within half of each plot, a vegetation control treatment was applied for the first 10 years by treating competing vegetation with herbicide. After 22 years, vegetation control significantly increased biomass and height of all planted species. The average height for northern red oak with vegetation control treatments was 884 cm with vs. 606 cm without; white oak was 837 cm with vs. 424 cm without; shortleaf pine was 1339 cm with vs. 1220 cm without. Moderate compaction increased average white oak height by 15% and severe compaction increased average height by 18% compared to no-compaction treatments. Compaction was not a significant treatment for red oaks or for shortleaf pines. However, the coarse fragments in the study soils appear to have muted much of the compaction to the soil’s fine-earth fraction and may have had the unintended effect of providing partial vegetation control. Whole-tree removal reduced average shortleaf pine heights by 6% vs. sawlog-only removal, while whole-tree + forest floor removal increased heights 3% compared to sawlog harvests. Organic matter removal was not a significant treatment for either oak species. Red oak survival probability was 0.79 with vegetation control vs. 0.34 without; white oak was 0.81 with vs. 0.65 without; shortleaf pine was 0.49 with vs. 0.45 without. Overall, vegetation control was the dominant factor driving survival and growth of oaks, and to a lesser degree, growth of shortleaf pine. Organic matter removal and compaction treatments had relatively little negative effect on height, indicating the resilience of these species to harvest-related disturbances in Ozark Highlands soils.

Decomposition of wood stakes in the Pacific Northwest after soil compaction and organic matter removal

Forest operations can affect soil productivity by impacting the amount and distribution of surface organic matter (OM) and changing the properties of surface mineral soil. The North American Long-Term Soil Productivity Study (LTSP) was developed to address such long-term changes after pulse disturbances associated with clearcut harvesting, soil compaction, and OM removal across a wide spectrum of forest sites. From 2000 to 2002 we established a study to assess the impact of four soil disturbance treatments on OM decomposition in the mineral soil on seven LTSP study plots from southern British Columbia, Canada to southern Oregon, USA. The soil treatments were combinations of two levels of compaction and organic matter removal: 1) removal of only merchantable logs [OM0] , 2) removal of all the forest floor and woody material [OM2], 3) no soil compaction after harvest [C0], and 4) “severe” soil compaction after harvest [C2]. Aspen (Populus tremuloides Michx.) and pine (Pinus taeda L.) wood stakes were inserted into the mineral soil of each treatment plot and in an adjacent unharvested control stand to a depth of either 20 or 30 cm (depending on soil depth). At the end of three years the soil compaction and the OM removal treatments had relatively little effect on pine or aspen stake decomposition at the British Columbia study sites. In the United States, soil compaction increased decomposition on the two study sites with coarse-texture mineral soil with surface OM intact. Three key findings were: (1) a strong positive relationship (p = 0.0009) between stake water content and stake mass loss, (2) aspen and pine stake decomposition was greater in the clearcut-LTSP treatments than in the unharvested stands, (3) the rehabilitation of the compacted soil treatment on the British Columbia study sites generally increased wood stake decomposition. However, overall, there were no consistent wood stake decay trends across all sites and LTSP treatments.

Soil compaction and organic matter removal effects on soil properties and tree growth in the Interior Douglas-fir zone of southern British Columbia

Silviculture systems and associated forest harvesting practices that affect the level of soil compaction and organic matter retained on a site will cause changes to soil properties and processes that may affect the growth of planted trees. We present results for soil conditions and tree growth after 15 years for 6 Long-term Soil Productivity Study (LTSP) installations in 2 distinct regions of the Interior Douglas-fir (IDF) biogeoclimatic zone in southern British Columbia (BC). In a 3 × 3 factorial design, three levels of compaction and organic matter removal were replicated in two distinct IDF regions that varied in parent material, but with similar climates. Each treatment was then split and planted with two different species, Douglas-fir and lodgepole pine. In each region, three unique sites (block), all within a radius of 50 km from one other, were installed with the same combination of treatment and species for a total of six replicates, three in each of two regions. Across IDF regions, tree heights on calcareous soils in the Rocky Mountains of south-eastern BC were 36% lower for Douglas-fir and 23% lower for lodgepole pine than on more acidic soils on the Thompson Plateau. There were varying differences across treatments in soil and foliar nutrient concentrations between IDF regions, primarily from regional parent material differences. However, nutrient deficiencies were apparent in both regions and may have limited growth, especially on the more calcareous sites. Increases to soil bulk density (27%) 1 year after compaction did not impact tree survival, height at Year-15, or chemical properties in foliar tissue or soil. Fewer growing season frost events and increased soil water availability during the seedling establishment period was a likely reason for a 25% increase in Douglas-fir survival at Year-15 with the whole tree + forest floor removal (OM3) treatment. However, whole tree + forest floor removal (OM3) also produced a 13–19% reduction in soil N, S, K, and mineralizable N when compared to both stem-only (OM1) and whole tree (OM2) harvesting treatments that kept the forest floor intact. Effects on forest productivity from soil compaction after 15 years appear to be overshadowed by the more prominent effect of organic matter removal treatments during stand establishment and early growth. Future work at these installations focusing on nutrient budget, forest health, and ecosystem carbon stock differences across treatments will provide valuable insight into silviculture and harvesting practices for different species and regions in the dry forests of southern BC.

Response of soil health indicators to organic matter removal and compaction manipulations at six LTSP sites in the Western US

Forest soils control many ecosystem services that enable and support primary forest productivity. Therefore, maintaining the health of the soil is critical to sustainable forest management. The long-term soil productivity (LTSP) experiment was initiated to increase our understanding of how the soil responds to pulse harvest disturbance and experiments have enabled tracking of soil health parameters across many diverse forest types. The purpose of this study was to investigate the effect of organic matter (OM) removal and compaction manipulations on soil health indicators at six long-term LTSP sites (study durations 16–25 years) in the Pacific Northwest and Northern California, USA.We hypothesized that only the most severe OM removal treatment would exhibit decreased soil nutrient pools and reduced biological processes and compaction would have less detrimental impact on soil properties than OM removal treatments. We collected mineral soil samples at six LTSP sites and measured soil health properties related to nutrient pools (total soil carbon (C) and nitrogen (N), active C) and biological processes (C and N mineralization and enzymatic potential activity). Our results indicate that the effects of OM removal treatments are more prominent than those effects of compaction treatments. Despite variation in inherent site properties, we did find consistent evidence that severe harvesting treatments may disrupt mineral soil functions and remain detrimental to most soil health measurements, even after 16–25 years. In contrast, bole-only and whole-tree removal treatments did not have this effect on soil parameters indicating these practices may not incur such long-lasting or deleterious effects. These results indicate the importance of reducing soil disruption due to harvesting in order to maintain ecosystem functions and highlights the importance of understanding the range of impact harvesting practices may have on forest soil health.