Amended Plots Research Articles

Identification and Isolation of Fungi in Abattoir and Poultry Amended Plots in Ilorin, Southern Guinea Savanna

Identification and Isolation of Fungi in Abattoir and Poultry Amended Plots in Ilorin, Southern Guinea Savanna

Use of Poultry Droppings and Wood Ash as Soil Amendment and its Effect on Soil Properties and Yield of Maize

Improvement in soil physicochemical and biological properties through the use of organic amendment is necessary for increased crop yield. This study evaluated the effects of poultry dropping, (PD) and wood ash (WA) on soil properties and maize grain yield in an ultisol in southeastern, Nigeria. The experiment was a randomized complete block design with four treatments replicated five times. The treatments were 0 t ha-1 (control), 4 t ha-1PD , 4 t ha-1 WA and 2 t ha-1 PD + 2 t ha-1 WA . Results of the study showed significant (p ≤0.05) decrease in bulk density and increase in total porosity in amended soil relative to the T1 (control). Similarly, soil chemical properties (Ca, Mg, pH, OM, avail P, Na, K) were significantly increased relative to the control. Application of the amendments increased maize grain yield relative to the control with highest increased observed in 4 t ha-1PD amended plots. The use of PD and WA for soil property improvement and increased crop yield is recommended for the studied soil.

Dependence of Thermal and Moisture Sensitivity of Soil Organic Carbon Decomposition on Manure Composition in an Inceptisol Under a 5‐Year‐Old Maize‐Wheat Cropping System

AbstractHydrothermal sensitivity of soil organic carbon decomposition in relation to global climatic changes is of great importance for C cycle in an agro‐ecosystem. To assess the sensitivities of SOC as affected by different organic sources and mineral fertilizer in Inceptisol, soil samples from a 5‐year‐old field experiment were collected from unfertilized control, 100% NPK, vermicompost, compost, and farmyard manure (FM) treated plots and analyzed for total organic C, labile C fractions and C mineralization kinetics by incubating soils at 25 and 35°C temperatures, and 0.33 and 1.0 bar soil moisture for 90 days. Compost and FM‐treated plots had ~23 and 22% higher total organic C than 100% NPK plots, respectively. Plots under vermicompost had similar C management index to FM but ~12% higher than compost. At 25°C temperature and 1.0 bar moisture, CO2 evolutions from vermicompost‐ and FM‐treated plots were ~29 and 11% higher than compost, respectively. Carbon decay rate was invariably higher in control and 100% NPK than organically amended plots. Temperature sensitivity of C was similar at 0.33 bar but different at 1.0 bar among the treatments. Moisture sensitivity of C in organic amended plots was similar at 35°C but different at 25°C, but their moisture sensitivity values were always higher than NPK. It could be concluded that manures with low C/N ratio and high N and P content would reduce C decay rate. Hence, to enhance C sequestration and reduce CO2 emissions in changing climatic situation, organic manure like vermicompost could be recommended.

Litter breakdown as a tool for assessment of the efficiency of afforestation and ash-aided phytostabilization on metal-contaminated soils functioning in Northern France.

The main objective of the study was to assess the efficiency of phytoremediation methods implemented for 14years on highly metal-contaminated soils. The different experimental strategies were plots planted with a tree mix or with a single tree species coupled or not with the use of fly-ashes as an amendment to limit metals mobility in soil. The breakdown of poplar litter on the four plots was monitored during 10months. In parallel, colonization of litter bags by functional groups of mesofauna (Collembola and Acari) was followed. Two mesh-sized litter bags were used to allow distinguishing microbial and mesofaunal actions on the litter breakdown. We observed the breakdown of litter in four studied plots. Litter breakdown occurred faster in 3-mm litter bags than 250μm ones during summer demonstrating the importance of mesofauna. Mixed plantation allowed faster litter breakdown than mono-specific plantation. A higher abundance of mesofauna and/or better abiotic conditions (moisture, shading…) could explain this result. Regarding litter breakdown and mesofauna, no significant difference was observed between the amended plots and those subjected to soil phytomanagement. However, communities of the studied area are disturbed since a low abundance of detritivores was observed. This could explain also the slower litter breakdown than expected in our study. To conclude, among the phytomanagement methods tested, mixed plantations could provide a benefit for the restoration of degraded soils. By contrast, the use of fly-ashes does not seem to have any effect on the functionality of ecosystem neither on the litter breakdown process nor on the abundance of mesofauna.

Evaluation of nematode suppression and yield improvement potential of organic substances in sweet potato crop

Objective: To investigate nematode suppression and yield improvement potential of two organic materials; poultry manure and chopped neem leaves in sweet potato production.Methodology and results: A factorial experiment mounted on Randomized Complete Block Design was conducted in 2014 and 2015 at Atebubu and Wenchi, prominent farming communities in the Brong Ahafo region of Ghana. The organic materials were applied on two sweet potato varieties; Apomuden and Santom pona. Poultry manure and neem leaves weighing 100g and 30g respectively were applied per stand. Plant population, nematodes population per 200-cm3 soil at planting and harvest, tuber galls, vine dry matter weight at harvest and yield were analyzed. Significantly, higher (P < 0.05) plant population was recorded at Wenchi compared to Atebubu in 2015. Control plots recorded significantly highest plant parasitic nematodes compared with the poultry manure and neem leaf treatments. Consistently, neem leaf amended plots recorded lowest population levels (67, 68 and 33) % and (84 and 84) % less Meloidogyne spp., P. brachyurus and H. multicintus and Meloidogyne spp., and P. brachyurus were extracted from neem leaf amended Santom pona plots compared with the control of Santom pona at Atebubu and Wenchi respectively. Poultry manure on Santom pona recorded the highest gall index, which was 78.8% more than observed on Santom pona treated with neem leaves. Neem leaf correlated positively with Apomuden and recorded the highest yield in 2014 at Atebubu, which was approximately 93% higher than the control of Santom pona, which yielded 0.9t/ha. The yield of neem leaf on Apomuden was significantly higher (35% and 41%) than neem leaf on Santom pona in 2014 and 2015 at Atebubu and Wenchi respectively.Conclusion and application of findings: Nematode management with synthetic products must be discouraged on grounds of mammalian toxicity and environmental degradation. The use of organic amendments should be encouraged for suppression of nematode population densities, improvement in yield and environmental friendliness. The latter option is sustainable and more importantly, tuber crops produced with organic amendments would be free from chemical residues.Keywords: Neem leaves, nematodes, poultry manure, sweet potato varieties

Polycyclic aromatic hydrocarbons in biochar amended soils: Long-term experiments in Brazilian tropical areas

The interest in charcoal for agricultural use (biochar) has sharply increased in recent years. However, biochar can contain groups of compounds such as polycyclic aromatic hydrocarbons (PAHs) that are considered persistent pollutants, and are formed concomitantly with biochar during its production by pyrolysis. Soil samples were collected in three experimental areas at different intervals (1, 3, 5 or 6 years) after the application of 16 Mg ha−1 of biochar. The total concentrations of PAHs; benzo[a]pyrene; and the estimated total cancer risk in biochar treated plots were larger than found in the control ones, but they decreased over time, equaling the control values after three years in the high C content soil (11.2 g C kg−1 soil), or after six years in the low C content soil (6.8 g C kg−1 soil). Nevertheless, the sum of PAH concentrations found in the biochar amended plots, in the range of 15.80–39.40 ng g−1, were around two orders of magnitude below the limits of prevention established by Brazilian legislation (8100 ng g−1) and some European regulations for soils (3000 ng g−1) and also lower than the observed in previous studies about biochar amended soils. Our results indicate that, under the conditions evaluated, the application of biochar to soil in the studied proportion (16 Mg ha−1, every six years) is safe concerning soil contamination by PAHs.

Cumulative Effect of Annual Additions of Uncomposted Oak and Maple Leaves on the Yield of Vegetables

ABSTRACTFor 22 years, plots were amended annually with oak (Quercus velutina Lam.) or sugar maple leaves (Acer saccharum Marsh.) in Mt. Carmel, CT on a loamy upland soil. Leaves were incorporated into the soil immediately after application in the fall. Yields of 12 different vegetable crops (lettuce, peppers, eggplant, tomatoes, edamame, delicata squash, spaghetti squash, onions, leeks, rutabaga, carrots, and beans) from these plots were compared to yields from unamended controls. All plots received equal amounts of fertilizer. There were no significant differences in vegetable yields with any of the crops between any of the treatments indicating there are no deleterious effects of annual applications of uncomposted leaves. Some soil characteristics such as organic matter and pH improved on the leaf amended plots. Study shows that annual applications of leaves to cropland (sheet composting) is a viable alternative for the disposal of leaves.

Performance of watermelon (Citrullus lanatus L.) in response to organic and NPK fertilizers

AbstractThe soil of North-Central Nigeria is home to many plant products that are used as industrial raw materials, and after processing their waste are often left in drainage channels, which ultimately find their way into rivers and streams where they pollute these water bodies, and sometimes some of these materials are burnt, which further aggravates global warming. In addition, the soil of the region is characterized by low organic matter content because of annual bush burnings, which reduce the low humus content of soils. Watermelon requires a fertile soil, which is high in organic matter content, while infertile soils yield an increased production of male flowers at the expense of female flowers, which results in low fruit set. Therefore, a study was carried out at the University of Ilorin Teaching and Research Farm, Ilorin, North-Central Nigeria, during the rainy seasons of 2013 and 2014 to assess the effect of different organic materials on the growth and yield of watermelon. The factors imposed were a control, NPK fertilizer and five organic materials (neem seed cake (NSC), jatropha seed cake (JSC), poultry manure (PM), compost manure (CM), and cow dung (CD)). The experiment was a randomized complete block design (RCBD) replicated thrice. Data collected on soil physico-chemical properties were: organic matter content, soil pH, organic carbon, total N, P, K, Ca, and Mg, bulk density (BD), micro porosity (MIP), macro porosity (MAP), and saturated hydraulic conductivity (KS). Plant parameters evaluated include growth (vine length and number of leaves) and yield (number of fruits per plant, fruit weight per plant, and yield ha−1). Results indicated that the organic matter content increased after the first year’s cropping and declined at the end of the study. The amended plots showed significantly higher values (P < 0.05) with respect to most soil physical properties (MIP), (MAP), and (KS), except the BD, where the values were lower. The bulk density particularly deteriorated on soils that were not organically amended. In addition, the soil chemical properties examined increased following the first year’s cropping, and thereafter declined at the end of the second-year cropping season. The response of watermelon showed that the two years’ yield data ranged between 334 and 402 t/ha, 306 and 390 t/ha, and 38.25 and 59.20 t/ha for NPK, poultry manure, and control treatments respectively. From the results, it was observed that the organic amendments were environmentally more friendly compared to the inorganic amendment (NPK fertilizer) in terms of positive effects on soil structural properties.

The Role of Soil Amendments on Population Dynamics of Insect Pests, Growth Parameters and Yield of Eggplant, Solanum melongena (L.) Moench

Loss of soil fertility as a result of continuous cropping on the same piece of land has necessitated the need to improve soil fertility for better crop yields. Inorganic and organic fertilizers have been used to improve soil fertility, however, excessive use of soil amendments improve vegetative growth of plants thereby attracting large numbers of insect pests. Cow dung and poultry droppings were used as soil amendments in a field experiment using eggplant Solanum melongena. The effects of these organic manures were compared with inorganic fertilizer (NPK) and a control where there was no application of soil amendment in a randomized complete block design with 3 replicates. Parameters studied were pests’ and their numbers, plant height, number of leaves per plant, leaf area, stem girth and yield. The major insect pests identified on the plant were Bemisia tabaci, Aphis gossypii, Leucinodes orbonalis and Eublemma olivacea. Bemisia tabaci and Aphis gossypii scores were significantly larger on cow dung and poultry manure plots. Leucinodes orbonalis and Eublemma olivacea numbers were not significantly different on the treated and control plots. Mean plant height, number of leaves and yield differed significantly among the soil amended plots. Even though soil amendments improve the nutrient content of the soil and the yield of crops it could lead to increase in pests numbers and damage caused to plants.

Nitrogen fertiliser replacement values for organic amendments appear to increase with N application rates

Nitrogen (N) supply from organic amendments [such as farmyard manure (FYM), slurries or crop residues] to crops is commonly expressed in the amendment’s Nitrogen Fertiliser Replacement Value (NFRV). Values for NFRV can be determined by comparison of crop yield or N uptake in amended plots against mineral fertiliser-only plots. NFRV is then defined as the amount of mineral fertiliser N saved when using organic amendment-N (kg/kg), while attaining the same crop yield. Factors known to affect NFRV are crop type cultivated, soil type, manuring history and method or time of application. We investigated whether long-term NFRV depends on N application rates. Using data from eight long term experiments in Europe, values of NFRV at low total N supply were compared with values of NFRV at high total N supply. Our findings show that FYM has a significant higher NFRV value at high total N supply than at low total N supply (1.12 vs. 0.53, p = 0.04). For the other amendment types investigated, NFRV was also higher at high total N supply than at low total N supply, but sample sizes were too small or variations too large to detect significant differences. Farmers in Europe usually operate at high rates of total N applied. If fertiliser supplements are based on NFRV of the manure estimated at low total N supply, N fertiliser requirements might be overestimated. This might lead to overuse of N, lower N use efficiency and larger losses of N to the environment.

Rice planted along with accumulators in arsenic amended plots reduced arsenic uptake in grains and shoots

An experiment was designed using phytoremadiation technology to obtain grains of rice safe for consumption. Sixteen plots of size 2 × 2 m were prepared (8 plots were treated with 50 mg kg−1 of sodium arsenate and rest 8 without any treatment). The study was done for two plantations (1st and 2nd plantation). Rice was planted with three accumulators (Phragmites australis, Vetiveria zizanioides and Pteris vitatta) in treated and untreated plot. Arsenic in grains of Actr (R + Pt, R + Ph and R + Vt) for 1st plantation was 0.4, 0.2 and 0.2 mg kg−1 where as in the case of wActr (Ras) it was 3 mg kg−1. In 2nd plantation the concentration of arsenic in grain of Actr (R + Pt, R + Ph and R + Vt) was 0.1, 0.1 and 0.1 mg kg−1 where as in the case of wActr (Ras) it was 2 mg kg−1. Significant differences in growth and yield parameters of rice between Actr and wActr in 1st plantation, while for 2nd plantation the activity was reduced in combinations except R + Pt and no significant difference was observed between Actr, Acntr and wActr. The study concluded that combinations of accumulators with crops could be useful for the survival and safe grains in As-contaminated soils but with some amendments in long-term remediation.

English

A study was conducted in two consecutive cropping seasons to assess the effect of biochar on soil properties and yield of cucumber (Cucumis sativus L) in an intensive cucumber–maize rotation based system of Abakaliki, Southeastern Nigeria. Five rates of hardwood biochar (0, 2.5, 3.75, 5 and 6.25 t ha-1) were used for the study. The study was laid out as a randomized complete block design (RCBD) with five treatments and four replications. Data were collected from both soil and plant parameters. Soil samples (0 to 20 cm) were collected before and at harvest from different plots for soil chemical analyses. Results obtained from the study showed significant (P<0.05) improvement in soil properties. Bulk density (BD) was significantly (p<0.05) decreased in biochar amended plots. Total nitrogen (N), available phosphorus (P), organic carbon (C), pH and exchangeable bases (K+, Ca2+, Mg2+ and Na+) were significantly (p<0.05) higher in biochar amended plots relative to the control. Biochar application significantly (p<0.05) increased vine length, number of fruits, fruit length and yield of cucumber compared to the control. On average, 6.25 t ha-1 rate of biochar application gave the highest improvement in soil properties while highest increase in yield and other agronomic parameters were observed in 5 t ha-1 rate of application. The study recommended 5 t ha-1 as the maximum rate of biochar application in the study area. Our results indicated that biochar application could be a possible way of improving soil properties and native soil carbon in the degraded ultisols and intensive cropping systems. Key words: Mineral fertilizer, organic inputs, small holder farms, soil productivity, sustainable agriculture.

Management of fusarium wilt of chickpea using brassicas as biofumigants

Phasing out of methyl bromide has resulted in the need for alternative strategies for the management of soilborne pests and diseases. Among several bioactive molecules, glucosinolates from Brassicaceae and their enzymatic degradation products, especially isothiocyanates formed by myrosinase enzyme, stand out as a promising alternative biofumigants. The effectiveness of biocidal compounds released from brassica species {Sinapis alba L. (syn. Brassica alba L.), B. nigra L., B. napus L., B. rapa L., B. juncea L. and B. carinata} tissue degradation on Fusarium oxysporum f. sp. ciceris (Padwick) Matuo and K.Sato (F.o.c; causal agent of chickpea wilt) growth in vitro, propagule attrition in soil and incidence of chickpea wilt in the field was carried out. Brassica alba L. was found to be the most toxic as it resulted in maximum percent mycelial growth inhibition of the pathogen followed by B. nigra L. and B. juncea L. tissues. Under glasshouse conditions, B. nigra was found most effective in reducing the colony forming units of the pathogen followed by B. alba L. and B. juncea L.. Lowest wilt severity under field conditions was observed in B. juncea L. tissues while greatest grain yield was produced in B. alba L. amended plots. The present study showed that the soil amendment with brassicas might be a feasible non-chemical approach to manage fusarium wilt of chickpea.

Effect of organic amendments on rice yield trend, phosphorus use efficiency, uptake, and apparent balance in soil under long-term rice-wheat rotation

ABSTRACTThe experiment was conducted in a 22nd cycle of rice-wheat rotation established in the eastern India with a randomized block designed with various combinations of inorganic and organic sources of nutrients like farm yard manure (FYM), paddy straw (PS), and green manure in rice crop only. Application of nitrogen, phosphorus, and potassium (NPK) and its combination with FYM, PS, and green manuring increased the grain yield of rice significantly. Rice yield declined only in control plots (−0.003 t ha−1 year−1), whereas positive yield trend was maintained in all the treatments. All organically amended plots showed a better uptake as well as use efficiencies of applied phosphorus (P) inputs over control. The apparent P balance showed positive value in control treatment over the years ranging from −4.8 to 24.8 kg ha−1 year−1. The positive yield trend of rice was maintained due to buildup of P from various organic inputs.

CO2 Emissions and Maize Biomass Production Using Digestate Liquid Fraction in Two Soil Texture Types

Abstract. The aim of this work was to evaluate the effects of soil texture and primary tillage type on soil CO2 emission and maize biomass production after digestate liquid fraction (DLF) spreading. The study was conducted in 2014 in two open fields at Terrasa Padovana (farm 1) and Bovolenta (farm 2) in the Veneto Region of Italy. Soil CO2 emission after digestate spreading was evaluated by comparing the effect of soil texture (sandy loam vs. clay loam) at farm 1 and the effect of long-term primary tillage management (&amp;gt;10 years) (ripping vs. plowing) in clay loam soil at farm 2. Unamended soil was considered the control at both farms. DLF was supplied before maize ( L.) sowing at a dose equal to 170 kg total nitrogen ha-1 using a splash-plate technique. DLF spreading determined a CO2 emission peak 1 h after spreading at both farms, with median emission values of 8.93 and 4.35 g m-2 h-1, respectively, from the sandy loam and clay loam soils at farm 1. At farm 2, primary tillage type did not exert a significant effect on CO2 emission peak, with a median value of 5.85 g m-2 h-1. About three days after DLF distribution, soil CO2 fluxes were less than 1 g m-2 h-1. The first soil harrowing and the first rainfall event after spreading determined significantly higher CO2 emissions from amended plots than from unamended plots for a few hours. At farm 1, soil CO2 emission during the maize growing season was significantly higher in the amended plots (+1.7 times) than in the unamended plots, which showed a median emission value of 0.29 g m-2 h-1; soil texture and tillage exerted no significant influence. Maize yield at dough stage was not significantly influenced by DLF at farm 1, with 22.7 ±1.6 Mg ha-1 and 18.7 ±2.8 Mg ha-1 in the clay loam and sandy loam soils, respectively. At farm 2, the distribution of DLF increased maize biomass production by +17% with respect to the unamended treatment that produced 18.0 ±2.4 Mg ha-1. Although the results reported in this article concern data from only one year, and further long-term experiments are needed to confirm our findings, they indicate that CO2 emissions after digestate distribution are lower in a clay loam soil than in a sandy loam soil and are not affected by primary tillage type. Keywords: Clay loam soil, Digestate splash-plate spreading, Plowing, Ripping, Sandy loam soil.

Influence of Tillage and Wood Ash on Zn and Fe Content of Soil, Castor Shoot and Seed

The effect of tillage methods (Mound, Ridge, Flat) and rates of wood ash on soil properties and yield of castor bean plant were studied in field trial at Abakaliki for 3 years cropping seasons. The experiment was a split plot in randomized complete block design with three tillage methods and four rates of wood ash (0 t∙ha-1, 2 t∙ha-1, 4 t∙ha-1 and 6 t∙ha-1), replicated three times. CropStat Version 7.2 computer software for data management developed primarily for the analysis of data from agricultural field trials was used to analyze data collected from the study and mean separation was done using least significant difference (LSD) at 5% alpha level. The findings from the study showed for soil heavy metal contents, it was observed that tillage methods had no effect on the heavy metals except for 1st year cropping result of Zn and 2nd year cropping result of Fe. The effect of tillage methods on heavy metal contents of castor shoot showed a significant difference P rd year result of Fe. The values obtained from Ridge and Flat were higher when compared with the value of Mound with regard to soil and castor shoot; heavy metal content with higher values was more observed in Flat method. The result of heavy metal content of seed indicated that tillage method had no effect on the heavy metal contents of the castor seed; the results of Fe, Zn in 1st and 2nd year planting season were not significant among the rates of wood ash applied. The effect of tillage and wood ash on heavy metal content of soil, castor shoot and seed was found to be significant (P -1 (Rd2), 4 t∙ha-1 (Rd4) and 6 t∙ha-1 (Rd6) on Fe 2nd year planting result of castor seed was statistically similar, while the result from Mound method was found to increase the seed uptake of the tested parameters. The observed values of the tested parameters (Fe, Zn) in wood ash amended plots in the three years’ study were beyond acceptable limits; hence reservation in the use of wood ash on continuous bases as soil amendment especially at higher rates. The findings also indicated that the use of wood ash as soil amendment on continuous basis on the same piece of land especially at higher rates might constitute pollution problems on the near future.

Effect of tillage and compost amendment on turfgrass establishment on a compacted sandy loam

Severe compaction of urban soil is a common problem that makes establishment and maintenance of turfgrass difficult. Compaction alleviation prior to seeding or sodding with turfgrass should lead to more persistent cover with reduced labor and maintenance inputs. A field study was conducted to determine the effects of several levels of soil remediation (tillage and tillage with compost amendment) on the establishment and persistence of low maintenance turfgrass grown on a severely compacted sandy loam. Four soil treatments consisting of two levels of tillage (none or subsoiler and Rotadairon) and three levels of compost amendment (0, 152, and 604 m3 ha−1 [0, 61, and 242 ft3 1,000 ft−2]) were applied prior to seeding on September 24, 2012. Initial establishment of plots amended with compost was delayed compared to tillage-only treatment and untreated control, likely due to a C:N ratio imbalance in the compost (C:N ratio = 41). Once the effect of the C:N imbalance had diminished, compost amended plots consistently sustained the greatest and highest quality turf cover. By early 2013 (seven months after seeding), turf quality and cover of the nonrestored plots (control) dropped sharply and remained at an unacceptable level for the remainder of the study. The tillage-only treatment provided acceptable turf quality and cover throughout most of 2013, but decreased to an unacceptable level by July of 2014, suggesting that compaction alleviation may be temporary when tillage is practiced on soil with limited organic matter (OM) content. Both of the soil restoration actions, soil tillage and amendment with compost, decreased soil bulk density, but the greatest reduction in bulk density occurred with OM addition. Compost amendment also improved soil OM content, pH, and nutrient availability. The treatment that produced the greatest improvement in soil properties measured (bulk density, volumetric water content, and nutrient availability) and turf cover was tillage in combination with compost amendment at the highest rate (604 m3 compost ha−1).

Modeling Copper and Cadmium Mobility in an Albeluvisol Amended with Urban Waste Composts

Core Ideas Mobility of Cu and Cd in compost‐amended soil was estimated using HYDRUS‐2D. Cu and Cd mobility was controlled by sorption in the tilled layer. Different sorption estimations were used to model trace metal leaching. EDTA/CaCl2 extracts ratio gave reliable Kd estimates for Cu but not for Cd. Most of the Cu and Cd mass remained in the tilled layer. Two experimental plots amended with a co‐compost of sewage sludge and green wastes (SGW) or with a municipal solid waste compost (MSW) were compared with a control plot without organic amendment (CONT) in terms of trace metals mobility. These plots were equipped with wick lysimeters, time‐domain reflectometry probes and tensiometers for 6 yr (2004–2010). Different soil structures due to tillage and compost incorporation were identified in the tilled layers and reproduced in HYDRUS‐2D for simulating water, Cu, and Cd transport. Two sorption estimation approaches were used, either assuming equilibrium between CaCl2 and ethylenediaminetetraacetic acid (EDTA) extractable metals (Kd‐1) or using equations based on pedotransfer functions assuming nonlinear sorption for Cu (Kf) and linear sorption for Cd (Kd‐2). Lysimeter data on Cu leaching were successfully reproduced with the Kd‐1 approach for the SGW and CONT plots (model efficiency coefficient ESGW = 0.97, ECONT = 0.95), while the MSW plot showed better fitting with the Kf approach (EMSW = 0.77), which could be explained by the less stable organic matter of the MSW compost because it takes into account organic matter components (dissolved organic C and soil organic matter). The Cd leaching was reproduced with the Kd‐2 approach for the two amended plots (ESGW = 0.12, EMSW = 0.80), while CONT simulation overestimated leaching. The percentage of measured Cu and Cd leached in reference to input mass was 0.6 and 2.7%, respectively, in the SGW plot compared with 5% for both metals in the MSW plot. Trace metal mobility appeared to be limited in the tilled layer by sorption to organic matter.

No tillage and sugar beet foam amendment enhanced microbial activity of degraded acidic soils in South West Spain

Ca-amendments are commonly applied to improve acid soils, whilst no-tillage (NT) has been widely recommended in soils where conventional tillage (CT) has led to losses of organic matter. However, the potential interactions between the two treatments are only partially known. Our study was conducted on a degraded soil located in SW Spain, in order to assess if the combination of Ca-amendment plus crop-tillage provides long term soil amelioration on microbial activity. To this end the effects of four different combinations of Ca-amendment and crop-tillage on selected key soil microbial properties were analyzed. The experimental design was a split-plot with four replicates. The main factor was the application or not of a Ca-amendment, sugar foam (SF) and control (C), and the second factor was crop-tillage, no tilled improved pasture (no tilled-IP) and conventional tillage forage crop (tilled-FC). Soil samples were collected from 2 soil depths after 7 years since the first SF application and after 1year from a repeated SF application. The use of the Ca-amendment meant a higher pH although this effect was not found in the combination Ca-amendment plus no-tilled. Total organic carbon (TOC) was highly influenced by tillage, being higher for no tilled plots. The interaction found between tillage and amendment suggested that the beneficial effect of the Ca-amendment on organic carbon is lost after tillage practices. A positive effect on microbial biomass carbon (MBC) was found after a second SF application for the no tilled plots in the upper layer however the effect was opposite in the deepest layer where no differences in TOC were found. After a year from a repeated SF application, a clear positive effect of no-tilled was observed on β-glucosidase, β-glucosaminidase and urease activities at the superficial layer. This fact was not found in these enzymatic activities when the amendment application effect was studied but an interaction between tillage and amendment showed that the Ca-amendment plus no-tilled combination was the most favorable option to increase the activities of these enzymes. Values of dehydrogenase were higher in amended plots than in control for both soil depths regardless of the sampling date, showing a pH effect on its activity. From our findings, no tillage plus a Ca-amendment appears to be the most suitable choice for ensuring suitable production, through the accumulation of soil organic matter (SOM) and the improvement of biological properties.

Effects of single sewage sludge application on soil phytoremediation

In European Union countries, disposal sewage sludge on agricultural lands is restricted by directives. Large-area degradation of surface soils in Europe is a major challenge to maintain and remediate due to their size and geomorphology, different historical uses and current biogeochemical conditions. These sites are often degraded with a mixture of contaminants mostly lacking a biologically active topsoil. The use of sewage sludge to restore such sites with soil organic matter and stabile plant cover have for long been explored, but the application is restricted by the chemical quality of the sewage sludge. Hence we designed a study to investigate the effect of a one-time amendment of a low-metal contaminated sewage sludge on a barren and contaminated soil to immobilize harmful trace metals and obtain sustainable plant cover. The present study was aimed to create plant cover on a barren soil by a single application of sewage sludge through the process of phytostabilization. The field experiment was conducted in the contaminated area near a zinc smelter with high metal concentration (cadmium, zinc, lead) and poor soil fertility. A single application of sewage sludge from food industry was made and forest species of Scots pine (Pinus silvestris L.), Norway spruce (Picea abies L.) and oak (Quercus robur L.) were used for phytoremediation. It was found that single application of sewage sludge was beneficial for development of plant cover and after a five years a significant increase in the biomass of trees (mainly spruce and pine) was achieved. Moreover, in the amended plots, the growth of various species of grasses, dicotyledonous plants, and spontaneous growth of birch was also observed. On control plots with no sewage sludge application, the planted trees gradually withered away during the same period. Sewage sludge from food industry provided plant nutrients effectively utilized by the plants. Its application also increased the water holding capacity in the test plots due to it contribution to soil organic matter. Compared to the control plots, the content of macroelements and carbon in soil was still higher at the end of the 5 year study. The high content of bioavailable macroelements in sewage sludge, poses a potential threat to their leaching and run-off into groundwater, contributing to the emergence of eutrophication of water bodies. However, the results of the experiments showed that the gradual release of macronutrients from sewage sludge were fully used by plants to stimulate their growth and development. The content of cadmium, zinc and lead in plant biomass was much lower compared to untreated plants. Also for treated plants the heavy metals were mainly accumulated in roots. The data from this field trial provided results supporting the use of high quality sewage sludge amendment for remediation of contaminated and barren soils, and large scale trials should be followed up on various degraded soil types.