Soil Health Parameters Research Articles

Conservation systems influence on soil properties in pumpkin production

AbstractVegetable crop production typically involves smaller land areas than agronomic production but relies heavily on intensive cultivation of soil to prepare the seedbed for planting and to manage weeds. Over time, extensive tillage can have negative effects on soil structure and microbial properties because soil is more prone to erosion when aggregation is reduced, and aggregates provide necessary habitat for a healthy microbial community. This 3‐yr study compared two types of systems: One was an intensively tilled control where no cover crops were planted, and the other type of system included cover crops and only one tillage event per year. For this study, no‐till is defined as the pumpkin cash crop no‐till planted into terminated cover crop residue. Treatments were a control (no‐cover crop, and tilled ≥ twice annually); plus seven conservation treatments including either fall‐planted or spring‐planted cover crops. Infiltration, bulk density, wet aggregate stability, microbial biomass carbon (MBC) and dissolved organic carbon (DOC) were determined. The main soil physical property that was affected by cover crops was an improvement in soil aggregation for the conservation systems, while lesser effects were observed for water infiltration and bulk density. While these changes did not occur immediately, soil aggregation showed differences between conservation treatments compared with the conventional control. Therefore, we conclude that the use of less tillage and a cover crop in a conservation system is generally beneficial as compared with a conventional system. This study illustrates the potential for improving some soil health parameters in as little as 2 yr.

Comprehensive impacts of diversified cropping on soil health and sustainability

ABSTRACT Conventional agriculture in the Midwest US lacks diversity, relies heavily on external inputs to maintain crop yields, and contributes to soil and water quality degradation. Using diverse crop rotations and incorporating livestock are promising solutions to these and other problems linked to current cropping systems dominated by maize (Zea mays L.) and soybean (Glycine max (L.) Merr.). To better understand how agricultural diversification comprehensively affects soil health and function, we compared 20 soil health parameters linked to critical soil ecosystem services in 1) a conventional 2-year maize-soybean rotation, and 2) a diverse 4-year maize-soybean-oat (Avena sativa L.)+alfalfa (Medicago sativa L.)-alfalfa rotation that periodically received cattle manure. The strongest and most salient improvements in soil health from the diversified, 4-year cropping system included: 8% reduction in soil resistance to root growth (p = .006), 16% increase in cation exchange capacity (p = .001), 157% increase in salt-extractable soil carbon (p = .024), and 62% increase in soil microbial biomass (p = .017). These comprehensive improvements in general soil functioning coincided with enhanced crop yields, reduced requirement for agricultural inputs, and decreased environmental impacts – all while maintaining profitability. Despite declines in cropping system diversity globally, but especially in the Midwest US, these results provide strong evidence for the benefits of diversification.

Environmentally sound alternative cropping systems for rice–wheat systems in North West India

Continuous cultivation of rice–wheat cropping system (RWCS) in Indo-Gangetic Plains of India is showing declining factor productivity coupled with many environmental problems. Diversifying the RWCS is one of the environmental friendly options for sustaining food production. Four crop rotations involving maize and sorghum in summer, wheat/potato/mustard in winter followed by short duration mung bean in late spring were studied to identify the most productive and economic combination from 2017 to 2020. Ranking of treatments by Tukey’s test of significance indicated that the maize-potato-wheat (16.49 t ha−1 year−1) combination was best in terms of system productivity calculated in terms of wheat equivalent yield (WEY). Maize-wheat-mung bean crop sequence was most profitable by having higher land use efficiency (LUE = 87.67%) and net return (NR = 1577.1 $ ha−1). The gross margin comparison revealed that maize-based crop sequences earned higher gross returns (23.17%), net return (93.66%), and B:C ratio (23.7%) than sorghum-based crop sequences. Soil health parameters were improved under the maize-mustard-mung bean system, which increased the organic carbon content by 28.65%, available N by 34.91% with saving of 47.67% in irrigation water. Adoption of alternate cropping sequences instead of rice–wheat, in the Indo-Gangetic Plains of India, could be more sustainable, profitable, and environment friendly.

Characterizing yield, nutrient elimination and fruit quality analysis of custard apple (Annona squamosa) under consortium of Azospirillum brasilense and vermicompost

The experiment was conducted to find out the effect of Azospirillum and vermicompost through application of different treatment combinations on eight years old bearing grafted plants of custard apple cv. Raydurg during 2018–2019. The results revealed that T10 (AZS @ 50 g + V.C. @ 10 kg/plant) was found optimally better in improvement of morphometric attributes. The application of (AZS @ 50 g + V.C. @ 10 kg/plant) in T10 treatment resulted in better crop at low inputs-use efficiency without having adverse effect on environment and offers an alternative for organic cultivation involving bioinnoculants. The studies harness the role of organic inputs along with AZS in optimization of fruit yield and maintenance of soil health parameters for efficient utilization of natural resources.

Continuous cropping legumes in semi-arid Southern Africa: Legume productivity and soil health implications

Abstract Legume agronomic research in Southern Africa has often focused on integrating legumes into smallholder cereal cropping systems, but there is limited information available on the feasibility and soil health implications of continuous cropping legumes in the region. Continuous legumes may be suitable in areas with large livestock populations where a premium is placed on high-quality forage, or where efforts are underway to reclaim degraded cropland. Our objectives in this study were to (i) evaluate the performance of diverse legumes under continuous cropping and conservation tillage management with no fertility inputs and (ii) assess the response of soil health parameters to continuous legumes in a semi-arid environment. A 4-year study was conducted in Limpopo, South Africa beginning in the 2011–2012 growing season in which 10 legume and fallow treatments were imposed in the same plots for 4 growing seasons. All legumes responded negatively in varying degrees to continuous cropping in terms of biomass and nutrient accumulation. Lablab (Lablab purpureus L.) was the top-performing legume in the study and accumulated 4.5–13 Mg ha−1 of biomass and 153–345, 11–34, and 75–286 kg ha−1 of N, P, and K, respectively. Lablab often outperformed natural fallow, while other legumes generally performed as well as or inferior to natural fallow, depending on species and growing season. Cowpea (Vigna unguiculata Walp) was especially incompatible with continuous cropping and averaged less than 252 kg ha−1 and 2.1 Mg ha−1 of grain and biomass, respectively, from 2012–2013 to 2014–2015. Continuous cropping did not lead to sustained improvements in soil health. By 2014–2015, soil organic matter for all treatments had either declined or resembled baseline values. Rates of potentially mineralizable N in cowpea, lablab, vining mucuna (Mucuna pruriens var. Utilis), natural fallow, and bare ground plots fell by 70–96% during the study. There was also evidence for lower recovery of leached K by legumes compared to natural fallow species. In conclusion, legumes, such as lablab, should be considered as continuous forages on marginal land in areas where high-quality forage is in demand, but continuous cropping legumes without fertility inputs are not an effective strategy for improving soil health on degraded cropland in this semi-arid region of Southern Africa. Future research efforts may focus on the grazing strategies and baling frequencies required to optimize annual biomass accumulation of continuous lablab to meet livestock demand and support smallholder livelihoods.

Influence of no-till cover crop management on soil thermal properties

Context Soil thermal properties influence soil health parameters and can help determine crop productivity with changing global atmospheric climate. Aim This study investigated the influence of no-till (NT) and cover crop (CC) management on soil thermal properties. Methods The study site was managed with NT. The CCs used included hairy vetch (Vicia villosa Roth.), crimson clover (Trifolium incarnatum L.), winter wheat (Triticum aestivum L.), winter peas (Lathyrus hirsutus L.), oats (Avena sativa), triticale (Triticale hexaploide Lart.), barley (Hordeum vulgare L.) and flax (Linum usitatissimum L.). Soil samples were collected at 0–10, 10–20, and 20–30 cm depths just prior to CCs being planted and also collected just before CCs were terminated. Treatments included NT CC and NT no cover crop (NC). Soil thermal properties (thermal conductivity [λ], volumetric heat capacity [C V], and thermal diffusivity [D]) were measured at 0, −33, and −100 kPa soil water pressures. Key Results CV at saturation was 13% higher under CC management compared with NC management. Averaged over all depths just before CC termination, λ and D at saturation were 21 and 35% higher, respectively, under NC management compared with CC management probably due to closer contact between soil particles. Conclusions Results from this study suggest CCs with NT management may be able to resist extreme soil temperature changes which could improve soil health and crop productivity in these systems. Implications NT and CC could improve crop productivity in the future but more in situ studies of soil thermal properties under these systems are needed.

Medium-term Impact of Organic and Microbial Fertilization on Production Efficiency and Fertility of Soil in an Apple Production System under North West Himalayan Region

ABSTRACT Continued exhaustive use of chemical fertilizers and environmental changes led to a decline in soil fertility and production efficiency, which eventually results in land degradation. The application of beneficial microorganisms and organic fertilizer may be an effective measure for sustainable agriculture production. Thus, a field experiment was conducted to investigate the impact of mineral and organic fertilizers (vermicompost/farm yard manure) supplemented with microbial inoculants on growth and soil health parameters of apple (Malus domestica cv. Oregon Spur) under medium density (4 m × 4 m) plantation. Nine integrated treatments of different combination of organic, inorganic and microbial inoculants were studied with four replications. Results revealed that plants received 75% of recommended (RD) NPK + Azospirillium had maximum increase in trunk cross section area (TCSA) and canopy volume (14.3 and 19.3%, respectively), average fruit yield (17.1 t ha−1) and production efficiency (0.92 g cm−2 TCSA) of apple during experiment period (2012–2015). Continuous 3 years of organic fertilization and microbial inoculants enhanced nutrient status of soil. Microbial biomass carbon, N and dehydrogenase activity of soil increased by 37%, 48% and 76%, respectively, in 50% of RD NPK + 25% N through FYM + 25% N through VC over control. Deviation from optimum percentage (DOP) index revealed 50% substitution of inorganic to organic fertilization (FYM and VC) is appropriate to correct deficiency of primary and secondary nutrients in leaves. Canonical correlation analysis revealed yield of apple was negatively correlated with DOP indices. In conclusion, 50% of inorganic fertilizers substituted through VC and FYM, and 25% inorganic fertilizers substituted through inoculation of Azospirillium, resulted higher fruit yield of apple in north west Himalayan region.

Single- versus Double-Species Cover Crop Effects on Soil Health and Yield in Mississippi Soybean Fields

Conservation management practices can improve soil health while minimizing deleterious effects of agriculture on the environment. However, adoption of these practices, particularly cover crops, is not widespread, as they often reduce crop yields compared to traditional management practices. The purpose of the current study was to determine if a two-species cover crop treatment of rye (Secale cereale L.) and crimson clover (Trifolium incarnatum L.) could increase soil health parameters and maximize soybean (Glycine max L.) yield greater than rye only in tilled and no-till Mississippi field soils. Enhanced microbial biomass and organic matter input from cover crops increased the activities of β-glucosidase, cellobiohydrolase, fluorescein diacetate hydrolysis, N-acetylglucosaminidase, and phosphatase in surface soils. Rye plus clover tended to elicit higher activities than rye only in no-till plots. Both cover crop treatments inhibited soybean yield in tilled plots by 11–25%. These results indicate that tillage exacerbates yield inhibition by cover crops in soybean and that double-species cover crop treatments were more consistent in increasing activities linked to nutrient cycling. Further study examining different combinations of cover crops in no-till systems is necessary to gain a better understanding of how they can be implemented to enhance soil health while maximizing crop yield.

Responses of leached nitrogen concentrations and soil health to winter rye cover crop under no-till corn-soybean rotation in the northern Great Plains.

Winter rye (Secale cereale L.) is an important cover crop (CC) in the northern Great Plains (NGP), yet concerns over its establishment under the variable weather conditions of this region are an important limitation for its widespread adoption. This study evaluated the impacts of no-till corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation with winter rye CC established in 2017 on (a) water quality (nitrate-N [NO3 - -N], ammonia-N [NH4 + -N], and total nitrogen [TN]) and (b) soil health parameters at the 0-to-15-cm depth. Data showed that rye CC biomass was 251kg ha-1 in 2018, 1,213kg ha-1 in 2019, and 147kg ha-1 in 2020, coinciding with contrasting growing degree days for rye CC (i.e., 1,458, 2,042, and 794, respectively), as a consequence of variable weather conditions. Water quality was not affected for the periods when rye growth was<300kg ha-1 . In the season when rye CC had greater biomass (1,213kg ha-1 ), significant reductions in leached NO3 - -N (19-20%) and TN (8.5-16%) concentrations were observed due to greater N uptake by rye CC (18.8kg N ha-1 ). Rye CC showed significantly (p ≤ .05) higher microbially active carbon ( ∼13%) and water-extractable organic N(∼11%) than the control treatment. Nonsignificant impacts on soil health indicators due to rye CC showed that the study duration (3 yr) may not be sufficient to see the beneficial impacts of CCs on soils. However, significant reductions in leached NO3 - -N and TN concentrations for one (2019) out of three study years suggest that rye with optimal growth has the potential of reducing N leaching and enhancing soil health for the NGP region.

Cover crops improve some, but not all, soil health indicators in horticultural rotations

Production of fruits and vegetables provides nutrient dense and high value crops. However, horticulture production is often very intensive and degrading to soil, with high levels of soil disturbance, high use of fertilizer inputs, and with prolonged periods of exposed soil. This can lead to increased soil degradation when compared to other types of cropping. We used a subset of the Atlantic Soil Health Laboratory’s database of on-farm soil samples collected between 2016 and 2018 to assess the impact of cover crop (CC) use in horticulture production in Nova Scotia on soil health. We analyzed 21 soil health parameters on soil collected from 14 fields, seven of which incorporated CCs in their crop rotation and seven of which used no CCs. The inclusion of CCs significantly increased permanganate oxidizable carbon (POX), soil respiration, autoclaved-citrate extractable (ACE) protein, residual soil nitrogen (N), and biologically available N. However, we also found that the variation in these parameters was greater when CCs were part of the rotation. This is likely attributable to the wide range of CC species used and differences in their management, such as the chosen termination method. While cover cropping is seen as a best management practice to improve soil health, simply using a CC in a horticulture rotation does not necessarily lead to improved soil health. Research trials on specific CC species and management to target soil degradation are needed to tailor recommendations to ensure the desired soil health outcomes can be achieved with CC use.

Can Wet Aggregate Stability and Texture Regulate Organic Carbon Stock in Alluvial Soils of East Champaran (Bihar)?

Aims: Here in this experiment, the investigation was done for the relationship among the various soil health parameters i.e., soil organic carbon (SOC), soil texture, and wet aggregate stability (WAS).&#x0D; Place and Duration of Study: Sample: Collection of soil samples were done from 0-15 cm depth from East Champaran is situated in Bihar and is located at 26038’N and 84054’E in the year 2019-2020.&#x0D; Methodology: Soil texture: 14g (+/- 0.1g) of sieved soil was added to a 50 ml centrifuge tube holding 42 ml of a dispersant 3% sodium hexametaphosphate solution follwed by 2 hr shaking and 0.053 mm sieved. Water stable aggregates: Each 0.25-mm sieve contained 4g of air-dried, 2-mm aggregate soil. Each sample's precise weight was recorded. The soil samples were dispersed for 3 minutes with 100 mL distilled water and then for 10 minutes with a 2 g/L sodium hexametaphosphate solution. Pre-weighed filter sheets were used to filter both solutions. Each filter paper was weighed after being oven-dried at 105°C.&#x0D; Soil organic carbon: The amount of soil organic carbon (SOC) was calculated using the Walkley and Black technique (1934).&#x0D; Results: Wet aggregate stability and soil organic carbon storage were shown to have a strong positive connection. Soil carbon stock in soils of East Champaran varied between 5.27-19.60 Mg ha-1 with an average of 12.98 Mg ha-1. WAS ranged from 3.82 to 36.43% with a mean of 16.11%. The results revealed that WAS increased with increase in SOC stock. This experiment also revealed that clay (%) and silt (%) directly affect WAS and hence enhance SOC storage.&#x0D; Conclusion: So, it can be concluded that WAS and soil texture directly and positively impact SOC storage in soils of East Champaran, Bihar.

Incorporation of rice residue and green gram cultivation saves nitrogen, improve soil health and sustainability of rice-wheat system

• Rice residue incorporation and green gram was tested on yield and soil health. • Nitrogen fertilizer up to 75 kg ha −1 was saved by green gram growing before rice. • Sustainability was enhanced by rice residue and green gram incorporation. • Organic C increased by rice residue and green gram incorporation after 7 years. • Saving upto75 Kg N ha −1 in Punjab and Haryana could save $45.1 million yearly. Rice-wheat cropping system and associated residue burning is a major cause of air pollution and soil health depletion in Northern India. This calls for urgent technological interventions to address the issue and improve the profitability of this cropping system. Objective was to study the effect of rice residue incorporation (RRI) and green gram inclusion (GGI) on amount of N applied, productivity and soil health in rice-wheat cropping (RWC) system. Combinations of RRI, nitrogen management and GGI with conventional rice-wheat rotation were tested for 7 years. Eleven treatments with combination of RRI, RR removal, GGI and N management were evaluated. Treatment effects on system productivity, profitability and soil health parameters were measured. Treatment R-W (-RR) - Gg + <25 % N to R and R-W (+RR) - Gg+ <25 % N to R +>25 % N to W produced maximum rice (7677 kg ha −1 ) and wheat yield (5949 kg ha −1 ), though non-significant (P > 0.05) compared to control (Rice = 7508 & Wheat = 5724 kg ha −1 ). Nitrogen fertilizer up to 75 kg ha −1 was saved when GGI was taken up before rice. GGI and RRI was sustainable in terms of higher sustainability value index (SVI = 0.78), wheat equivalent yield (WEY = 20.0 t ha −1 ) and production efficiency (PE = 57.5 kg ha −1 day −1 ). The treatments with GGI + RRI produced 1015$ additional net returns with more than double B:C ratio. Soil health in the form of SOC (0.42 %) and available N (152.6 kg ha −1 ) were also improved with GGI + RRI in treatment R-W (+RR) - Gg+ <25 % N to R +>25 % N to W. Adoption of RRI + GGI over 3.64 m ha area under RWC system of studied ecology may save 45.1 million US $ worth N fertilizer annually in addition to substantial reduction in air pollution.

Phytostabilization of a contaminated military site using Miscanthus and soil amendments.

Military activities can contaminate productive land with potentially toxic substances. The most common trace metal contaminant on military bases is lead (Pb). A field experiment was begun in 2016 at Fort Riley, KS, in an area with total soil Pb concentrations ranging from 900 to 1,500mg kg-1 and near-neutral pH. The main objectives were to test the potential of Miscanthus sp. for phytostabilization of the site and to evaluate the effects of soil amendments on Miscanthus growth, soil-plant Pb transfer, bioaccessibility of soil Pb, and soil health. The experimental design was a randomized complete block, with five treatments and four replications. Treatments were (a) existing vegetation; (b) Miscanthus planted in untilled soil, no amendments; (c) Miscanthus planted in tilled soil; (d) Miscanthus planted in tilled soil amended with inorganic P (triple superphosphate applied at 5:3Pb:P); and (e) Miscanthus planted in tilled soil amended with organic P (Class B biosolids applied at 45 Mg ha-1 ). Tilling and soil amendments increased dry matter yields only in the establishment year. Total Pb uptake, plant tissue Pb concentration, and soil Pb bioaccessibility were significantly less in the Miscanthus plots amended with biosolids than the Miscanthus plots with no added P across all 3 yr. Enzyme activities, organic carbon, and microbial biomass were also greater in biosolids-treated plots. Results show that planting-time addition of soil amendments to Pb-contaminated soil supported Miscanthus establishment, stabilized and reduced bioaccessibility of soil Pb, reduced concentration and uptake of Pb by Miscanthus, and enhanced soil health parameters.

Value of integrating perennial forage seed crops in annual cropping sequences

AbstractCropping sequences integrating perennial forages and annual crops can generate multidimensional agroeconomic and environmental benefits. A 4‐yr cropping sequence study was conducted from 2013 to 2016 to evaluate the relative merits of various cropping sequences. Three forage seed crops (creeping red fescue [Festuca rubra L.], alsike clover [Trifolium hybridum L.], and red clover [Trifolium pratense L.]) and four annual food crops (wheat [Triticum aestivum L.], canola [Brassica napus L.], barley [Hordeum vulgare L.], and pea [Pisum sativum L.]) were used to generate eight different cropping sequence treatments, which were split into three levels of nitrogen (N): 0, 45, and 90 kg ha−1. The seed yields of different crops were expressed as canola equivalent yield (CEY) and summed for 4‐yr cropping sequences. Economic benefits for 4‐yr cropping sequences were calculated using the input–output price scenarios of individual years. The highest CEY, gross return, and gross margin over partial variable costs were obtained from creeping red fescue‐based cropping sequences, irrespective of N application rates. Based on CEY and gross margins, the merit order is ranked as creeping red fescue‐based sequences &gt; high diversity annual crop sequences ≈ alsike clover‐based sequence ≈ wheat–canola alternating sequence &gt; continuous canola sequence. The clover‐based sequences had positive effects on the performance of succeeding crops of wheat and canola. Among the annual crop‐based sequences, economic profitability increased with the diversification from continuous canola through wheat–canola alternation to pea–barley–wheat–canola in the sequence. Further study investigating soil health and greenhouse gas emissions parameters is warranted to elucidate multidimensional agroecosystem services of diversified perennial forage seed crop‐based cropping sequences compared with annual crops‐based sequences.

Soil health and grain yield impacts of climate resilient agriculture projects: Evidence from southern Malawi

CONTEXTClimate resilient agriculture (CRA) projects like watershed restoration efforts can enhance agricultural systems' resilience to climate change and extreme weather shocks by improving soil health and grain yields in vulnerable communities. One such project, Wellness and Agriculture for Life Advancement (WALA) implemented watershed restoration across eight districts in southern Malawi from 2009 to 2014 to improve degraded soils and boost grain yields. Yet, rigorous analyses of soil health and grain yield impacts of CRA projects remain limited in southern Malawi, other dryland areas of sub-Saharan Africa (SSA), and elsewhere. OBJECTIVEUsing the watershed restoration context of the WALA project as a case study, we estimated the core determinants of CRA program participation and the impacts of participation on soil health and grain yields among smallholder farmers in southern Malawi in 2016. METHODSWe applied an endogenous switching regression with a control function approach to primary survey data from a sample of 808 agricultural households from five WALA districts to estimate the determinants of participation in the CRA project, and the impacts on soil health parameters and grain yields, accounting for endogeneity and selectivity bias. RESULTS AND CONCLUSIONWe found that participation in the project improved grain yields in terms of maize (Zea mays) by 61% in 2016 – a drought year, and soil health parameters including nitrogen, potassium, soil organic matter, and soil organic carbon by 41%, 31%, 57%, and 44% respectively. Results suggest that CRA projects are essential devices for improving soil health and grain yields in dryland areas such as southern Malawi, elsewhere in SSA, and beyond. SIGNIFICANCEThis research shows that CRA projects can enhance sustainable agriculture by improving soil health parameters, increasing grain yields, and building agricultural systems' resilience to climate change and extreme weather shocks, thereby contributing to the Sustainable Development Goals on hunger and climate action in dryland areas of developing countries.

Carbon Mineralization Dynamics of Organic Materials and Their Usage in the Restoration of Degraded Tropical Tea-Growing Soil

Understanding carbon mineralization dynamics of organic amendments is essential to restore degraded lands. This study focused on the restoration potentials of tea-growing soils using organic materials available in tea ecosystems. The Selangor-Briah soil series association (Typic Endoaquepts) consisted of a high- (soil A) and a low-carbon (soil B) soils were incubated with different organic materials and released carbon dioxide (CO2) measured. Two kinetic models were applied to depict the mineralization process. Soil health parameters including microbial biomass carbon and nitrogen, dehydrogenase and catalase activities were determined to assess the restoration potentials. The parallel first-order kinetic model fitted well for all amendments. Gliricidia markedly enhanced the net cumulative CO2 flux in both soils. Charged biochar, tea waste and Gliricidia improved the microbial biomass carbon by 79–84% in soil A and 82–93% in soil B, respectively. Microbial quotients and biomass nitrogen were increased over 50 and 70% in amended soils, respectively. Dehydrogenase activity was significantly accelerated over 80% by compost, charged biochar and tea waste. Charged biochar remarkably increased the soil catalase activity by 141%. Microbial biomass, dehydrogenase and catalase activities, and cumulative CO2 flux were positively correlated (r &gt; 0.452) with one another. The studied amendments showed greater potential in improving the soil quality, while charged biochar, raw biochar and compost enrich the soil recalcitrant C pool ensuring the soil health in long term. Even though biochar sequesters carbon, it has to be charged with nutrients to achieve the soil restoration goals.

Biochar and Its Broad Impacts in Soil Quality and Fertility, Nutrient Leaching and Crop Productivity: A Review

Biochar is gaining significant attention due to its potential for carbon (C) sequestration, improvement of soil health, fertility enhancement, and crop productivity and quality. In this review, we discuss the most common available techniques for biochar production, the main physiochemical properties of biochar, and its effects on soil health, including physical, chemical, and biological parameters of soil quality and fertility, nutrient leaching, salt stress, and crop productivity and quality. In addition, the impacts of biochar addition on salt-affected and heavy metal contaminated soils were also reviewed. An ample body of literature supports the idea that soil amended with biochar has a high potential to increase crop productivity due to the concomitant improvement in soil structure, high nutrient use efficiency (NUE), aeration, porosity, and water-holding capacity (WHC), among other soil amendments. However, the increases in crop productivity in biochar-amended soils are most frequently reported in the coarse-textured and sandy soils compared with the fine-textured and fertile soils. Biochar has a significant effect on soil microbial community composition and abundance. The negative impacts that salt-affected and heavy metal polluted soils have on plant growth and yield and on components of soil quality such as soil aggregation and stability can be ameliorated by the application of biochar. Moreover, most of the positive impacts of biochar application have been observed when biochar was applied with other organic and inorganic amendments and fertilizers. Biochar addition to the soil can decrease the nitrogen (N) leaching and volatilization as well as increase NUE. However, some potential negative effects of biochar on microbial biomass and activity have been reported. There is also evidence that biochar addition can sorb and retain pesticides for long periods of time, which may result in a high weed infestation and control cost.

Nitrogen Fertilizer Effects on Microbial Respiration, Microbial Biomass, and Carbon Sequestration in a Mediterranean Grassland Ecosystem

Natural grasslands represent the second largest ecosystem in Turkey. However, the impact of varying nitrogen (N) fertilization rates on overall soil health indicators have not been reported in the country. A 2-year study was conducted in the Kahramnmaras Plateau region in Turkey to evaluate the impacts of seven N application rates [i.e., 0 (N0), 50 (N50), 100 (N100), 150 (N150), 200 (N200), 250 (N250), and 350 (N350) kg N ha−1] on physical, chemical, and biological parameters of soil health. Nitrogen addition decreased bulk density by 8–12%, and increased aggregate stability by 3–5% and EC up to 110%. Application of ≥ 100 kg N ha−1 increased soil porosity up to 6.7%. Soil pH and C:N ratios were not affected by N addition. The lowest plant available water occurred with the N0 and N50 treatments, decreasing around 24% and 17% compared to N300. Soil organic carbon, total nitrogen, and C and N stocks increased with increasing N addition. Application of N300 rates increased C stocks between 4 and 34%, and N stocks between 15 and 22% compared to all other treatments. Compared to control, N250 increased microbial biomass carbon by 349% and nitrogen by 250%. Microbial respiration in the N250 and the N300 treatments was 97% and 129% greater than control. Addition of N fertilization for a first time in a grassland ecosystem with a previous history of long-term overgrazing, even at low rates, positively impacted several parameters of soil health, a positive impact that could ensure a greater sustainability of these fragil systems over the long-term.

On-farm assessment of cover cropping effects on soil C and N pools, enzyme activities, and microbial community structure

AbstractIntroducing cover crops (CC) in annual cropping systems can promote nutrient cycling and improve soil health. However, impacts of CC on soil health indicators vary and depend on the duration of CC, cropping systems, and other environmental conditions. We performed an on-farm assessment of cover cropping impacts on soil health indicators including C and N pools, enzyme activities, and microbial community structure under different no-till maize-based cropping systems (maize (Zea mays L.)–soybean (Glycine max L.) [CS], CS-winter wheat (Triticum aestivum L.) [CSWw], and maize-oats (Avena sativa L.) [CO]). At five farms, fields with different durations of CC were compared to adjacent no CC (NCC) fields. In general, long-term CC enhanced the soil health parameters compared to NCC. Long-term (20-year) winter rye CC had higher water-extractable C and N content, enzyme activities (β-glucosidase (1.2 times greater), urease (5.5 times greater), acid (1.5 times greater) and alkaline (4 times greater) phosphatase, arylsulfatase (0.8 times greater) and fluorescein diacetate (FDA) (0.7 times greater)) and soil bacterial community abundance (1.2 times greater). Short-term (3–6 years) legume and grass CC mixtures increased β-glucosidase (0.9 times), acid (0.7 times) and alkaline (1.5 times) phosphatase, arylsulfatase (3 times), FDA (0.8 times) activities and total phospholipid fatty acid (1.6 times) concentration. However, short-term (3–6 years) winter rye, legume and brassica mixtures did not significantly alter soil microbial community structure. This study showed that implementation of CC for &gt;6 years promoted C, N, S, and P cycling that are beneficial to soil health in maize-based cropping systems.

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.