Response of Rice Cultivars to Elevated Air Temperature and Soil Amendments: Implications towards Climate Change Adaptations and Mitigating Global Warming Potentials

Global mean surface air temperature is expected to increase 1.1˚C - 6.4˚C by the end of 21st century which may affect rice productivity and methane emissions in the future climate. This experiment was conducted to investigate the response of rice cultivars to elevated air temperature (+1.5˚C higher than ambient) and soil amendments in regards to rice yield, yield scaled methane emissions and global warming potentials. The experimental findings revealed that replacement of inorganic fertilizers (20% - 40% of recommended NPKS) with Vermicompost, Azolla biofertilizer, enriched sugarcane pressmud, rice husk biochar and silicate fertilization increased rice yield 13.0% - 23.0%, and 11.0% - 19.0% during wet aman and dry boro season, respectively. However, seasonal cumulative CH4 fluxes were decreased by 9.0% - 25.0% and 5.0% - 19.0% during rainfed wet aman and irrigated dry boro rice cultivation, respectively with selected soil amendments. The maximum reduction in seasonal cumulative CH4 flux (19.0% - 25.0%) was recorded with silicate fertilization and azolla biofertilizer amendments (9.0% - 13.0%), whereas maximum grain yield increment 10.0 % - 14.0% was found with Vermicompost and Sugarcane pressmud amendments compared to chemical fertilization (100% NPKS) treated soils at ambient air temperature. However, rice grain yield decreased drastically 43.0% - 50.0% at elevated air temperature (3˚C higher than ambient air temperature), eventhough accelerated the total cumulative CH4 flux as well as GWPs in all treatments. Maximum seasonal mean GWPs were calculated at 391.0 kg CO2 eq·ha−1 in rice husk biochar followed by sugarcane pressmud (mean GWP 387.0 kg CO2 eq·ha−1), while least GWPs were calculated at 285 - 305 kg CO2 eq·ha−1 with silicate fertilizer and Azolla biofertilizer amendments. Rice cultivar BRRI dhan 87 revealed comparatively higher seasonal cumulative CH4 fluxes, yield scaled CH4 flux and GWPs than BRRI dhan 71 during wet aman rice growing season;while BRRI dhan 89 showed higher cumulative CH4 flux and GWPs than BINA dhan 10 during irrigated boro rice cultivation. Conclusively, inorganic fertilizers may be partially (20% - 40% of the recommended NPKS) replaced with Vermicompost, azolla biofertilizer, silicate fertilizer and enriched sugarcane pressmud compost for sustainable rice production and decreasing GWPs under elevated air temperature condition.

Residual Effects of Phosphate Amendments on Rainfed Rice (Oryza sativa L.) Nutrition and Soil Properties in Three Agroecological Zones of Côte d’Ivoire

A study was conducted in Côte d’Ivoire to assess the after-effect of phosphate amendments on rice yields and soil properties. Eight types of amendments, composed of Moroccan phosphate rock (PRM) and triple superphosphate were tested in three agroecological zones over three consecutive years of cultivation. This study revealed that the application of Moroccan phosphate rock (PRM) and/or triple superphosphate (TSP) did not significantly affect soil cation exchange capacity (CEC) and organic carbon (Corg) content. However, there was a negative residual effect of PRM-rich treatments on soil pH and K and N content, but the impact varies depending on the characteristics of the soils studied. Furthermore, nutrient losses, notably nitrogen from −17.5 to −267.7 kg/ha and potassium (−0.1 to 0.7 kg/ha), were observed in all treatments. Only phosphorus showed a positive balance of +49.56 to +52 kg/ha in PRM-rich treatments. Treatment T3, composed of 80% RPM and 20% TSP, was the most effective in all zones, with a relative increase in grain yields of over 100% compared to the control. These results suggest that the input of natural phosphate rock can significantly improve rice yields and soil properties in the studied agroecological zones in Côte d’Ivoire.

Prospects and limitations of soil amendment and irrigation techniques for the water-saving public urban greenery and ephemeral weed management in the sandy soils of the United Arab Emirates

Public urban greenery greatly contributes to the residential and tourist value of cities in the Gulf Region,but due to the hyper-arid climatic conditions,the cost of irrigation and plant maintenance is very high.Existing strategies to reduce the monetary and ecological costs involve the cultivation of native xerophytic plantations,and/or the use of soil improvers to increase water-and nutrient-holding capacity of the sandy soils.Various soil improvers based on mineral,organic,or synthetic materials have entered the United Arab Emirates(UAE)market in recent years,but there is considerable uncertainty about how they should best be used in combination with ornamental plant stands involving xerophytic native plants.The present study investigated the effect of soil amendment and deep pipe irrigation on perennial ornamental plant stands involving native plants(Tephrosia appolinea(Gel.)Link in combination with Aerva javanica(Burm.f.)Juss.ex Schult.)and native-exotic plants(T.appolinea in combination with Ruelia simplex C.Wright)either or not topsoil and subsoil amendment with bentonite and hydrophobic sand under the irrigation water supply of less than 50%of reference evapotranspiration(ET0).After one year of cultivation,T.appolinea and A.javanica(native vs.native)produced high biomass and exhibited high water use efficiency(WUE)as compared with T.appolinea and R.simplex(native vs.exotic)combination given that no significant differences were found under the soil amendment treatments.All stands thrived under irrigation water supply far below what is usually supplied to exotic ornamental stands in public parks of the Al Ain City,the UAE.However,subsoil amendment in combination with deep pipe irrigation reduced the occurrence of weeds and increased the overall plant rooting depth.Our results suggest that subsoil amendment and irrigation up to 60-80 cm depth can potentially control ephemeral weed infestation,which is a great challenge in various plant production systems of the Gulf Region.The results of the present study suggest that the impact of soil amendment on the WUE of exotic plants is marginal and might not be economically justified.Replacing exotic with native ornamental plant species seems to have a far greater water-saving potential than the amendment of the soil,while weeds can be suppressed in the absence of topsoil moisture.

Optimization of Diesel and Crude Oil Degradation in a Ghanaian Soil Using Organic Wastes as Amendment

Soil contamination by hydrocarbons poses numerous environmental, health and agricultural problems. The degradation of these pollutants can occur naturally but very slowly. It is therefore generally necessary to stimulate this degradation by different means. Thus, this study aimed to improve the bio-degradation of diesel and crude oil in a Ghanaian soil by biostimulation. For this, the sampled soil was characterized by standard methods and contaminated with diesel and crude oil at a proportion of 1% (w/w). Then, contaminated soil samples were supplemented with biochar-compost, poultry manure or cow dung at the proportion of 10% (w/w). Periodically, fractions of these samples were taken to evaluate the density of hydrocarbon utilizing bacteria (HUB) and the residual quantities of diesel or crude oil. The characteristics of the soil used show the need for supplementation for better degradation of hydrocarbons. The results of the study show that supplementing the soil with organic substrates increases HUB loads in soils contaminated by diesel and crude oil. They also show that the residual quantities of diesel and crude oil are generally significantly lower in supplemented soils (p = 0.048 and p < 0.0001 respectively). In addition, the study shows that degradation was generally greater in soils contaminated by diesel compared to those contaminated by crude oil, especially at the end of the study.

Effect of amendments on growth and metal uptake of giant reed(Arundo donax L.) grown on soil contaminated by arsenic,cadmium and lead

The effects of five amendments such as acetic acid（AA）, citric acid （CA）, ethylenediamine tetraacetic acid （EDTA）, sepiolite and phosphogypsum on growth and metal uptake of giant reed （Arundo donax L.） grown on soil contaminated by arsenic （As）, cadmium （Cd） and lead （Pb） were studied. The results showed that the shoot biomass of giant reed was enhanced by 24.8% and 15.0%, while superoxide mutase and catalase activities slightly varied when adding 5.0 mmol/kg CA and 2.5 mol/kg EDTA to soil as compared to the control, respectively. The concentrations of As, Cd and Pb in shoots were remarkably increased by the addition of 2.5 mmol/kg AA and CA, 5.0 mmol/kg EDTA, and 4.0 g/kg sepiolite as compared to the control. The accumulations of As and Cd were also significantly enhanced in the above condition, while the shoot Pb accumulation was noticeably enhanced by amending with 4.0 g/kg sepiolite and 8.0 g/kg phosphogysum, respectively. The results suggested that AA, CA and sepiolite could be used as optimum soil amendments for giant reed remediation system.

Effects of several amendments on rice growth and uptake of copper and cadmium from a contaminated soil

Heavy metals in variable charge soil are highly bioavailable and easy to transfer into plants. Since it is impossible to completely eliminate rice planting on contaminated soils, some remediation and mitigation techniques are necessary to reduce metal bioavailability and uptake by rice. This pot experiment investigated the effects of seven amendments on the growth of rice and uptake of heavy metals from a paddy soil that was contaminated by copper and cadmium. The best results were from the application of limestone that increased grain yield by 12.5-16.5 fold, and decreased Cu and Cd concentrations in grain by 23.0%--50.4%. Application of calcium magnesium phosphate, calcium silicate, pig manure, and peat also increased the grain yield by 0.3-15.3 fold, and effectively decreased the Cu and Cd concentrations in grain. Cd concentration in grain was slightly reduced in the treatments of Chinese milk vetch and zinc sulfate. Concentrations of Cu and Cd in grain and straw were dependent on the available Cu and Cd in the soils, and soil available Cu and Cd were significantly affected by the soil pH.

Impacts of chemical fertilizer reduction and organic amendments supplementation on soil nutrient,enzyme activity and heavy metal content

Excessive use of agro-chemicals （such as mineral fertilizers） poses potential risks to soil quality. Application of organic amendments and reduction of inorganic fertilizer are economically feasible and environmentally sound approaches to de- velop sustainable agriculture. This study investigated and evaluated the effects of mineral fertilizer reduction and partial substitution of organic amendment on soil fertility and heavy metal content in a 10-season continually planted vegetable field during 2009-2012. The experiment included four treatments： 100% chemical fertilizer （CF100）, 80% chemical fertilizer （CF80）, 60% chemical fertilizer and 20% organic fertilizer （CF60＋OM20）, and 40% chemical fertilizer and 40% organic fertilizer （CF40＋OM40）. Soil nutrients, enzyme activity and heavy metal content were determined. The results showed that single chemical fertilizer reduction （CF80） had no significant effect on soil organic matter content, soil catalase activity and soil heavy metal content, but slightly reduced soil available N, P, K, and soil urease activity, and significantly reduced soil acid phosphatase activity. Compared with CF100, 40 or 60% reduction of chemical fertilizer supplemented with organic fertilizer （CF60＋OM20, CF40＋OM40） significantly increased soil organic matter, soil catalase activity and urease activity especially in last several seasons, but reduced soil available P, K, and soil acid phosphatase activity. In addition, continu- ous application of organic fertilizer resulted in higher accumulation of Zn, Cd, and Cr in soil in the late stage of experiment, which may induce adverse effects on soil health and food safety.

Soil microbial characteristics and yield response to partial substitution of chemical fertilizer with organic amendments in greenhouse vegetable production

Greenhouse vegetable production has been characterized by high agricultural inputs, high temperatures, and high cropping indexes. As an intensive form of agriculture, nutrient cycling induced by microbial activities in the greenhouses is relatively different from open fields in the same region. However, the responses of soil microbial biomass carbon （MBC） and nitrogen （MBN）, enzyme activities, microbial community composition, and yield to organic amendment are not well understood. Therefore, a 5-year greenhouse tomato （Solanum lycopersicum Mill.）-cucumber （Cucumis sativus L.） rotation experiment was conducted. The field experiment comprised 5 treatments： 4/4CN （CN, nitrogen in chemical fertilizer）, 3/4CN＋1/4MN （MN, nitrogen in pig manure）, 2/4CN＋2/4MN, 2/4CN＋1/4 MN＋1/4 SN （SN, nitrogen in corn straw） and 2/4CN＋2/4SN. The amounts of nitrogen （N）, phosphorus （P2O5）, and potassium （K2O） were equal in the five treatments. Starting with the fourth growing season, the optimal yield was obtained from soil treated with straw. MBC, MBN, phospholipid fatty acid （PLFA） profiles, and enzyme activities were significantly changed by 5 years of substitution with organic amendments. Redundancy analysis showed that MBC accounts for 89.5 and 52.3％ of the total enzyme activity and total community variability, respectively. The activities of phosphomonoesterase, N-acetyl-glucosaminidase, and urease, and the relative abundances of fungi, actinomycetes, and Gram-negative bacteria were significantly and positively related to vegetable yields. Considering the effects of organic amendments on soil microbial characteristics and vegetable yield, 2/4CN＋1/4MN＋1/4SN can improve soil quality and maintain sustainable high yield in greenhouse vegetable production.

Synergistic Effects of Nitrogen Amendments and Ethylene on Atmospheric Methane Uptake under a Temperate Old-growth Forest

An increase in atmospheric nitrogen （N） deposition can promote soil acidification, which may increase the release of ethylene （C2H4） under forest floors. Unfortunately, knowledge of whether increasing N deposition and C2H4 releases have synergistic effects on soil methane （CH4） uptake is limited and certainly deserves to be examined. We conducted some field measurements and laboratory experiments to examine this issue. The addition of （NH4）2SO4 or NH4Cl at a rate of 45 kg N ha-1 yr-1 reduced the soil CH4 uptake under a temperate old-growth forest in northeast China, and there were synergistic effects of N amendments in the presence of C2H4 concentrations equal to atmospheric CH4 concentration on the soil CH4 uptake, particularly in the NH4Cl-treated plots. Effective concentrations of added C2H4 on the soil CH4 uptake were smaller in NH＋4 -treated plots than in KNO3-treated plots. The concentration of ca 0.3 μl C2H4 L-1 in the headspace gases reduced by 20% soil atmospheric CH4 uptake in the NH4Cl-treated plots, and this concentration was easily produced in temperate forest topsoils under short-term anoxic conditions. Together with short-term stimulating effects of N amendments and soil acidification on C2H4 production from forest soils, our observations suggest that knowledge of synergistic effects of NH＋4 , rather than NO3- , amendments and C2H4 on the in situ soil CH4 uptake is critical for understanding the role of atmospheric N deposition and cycling of C2H4 under forest floors in reducing global atmospheric CH4 uptake by forests. Synergistic functions of NH4＋ -N deposition and C2H4 release due to soil acidification in reducing atmospheric CH4 uptake by forests are discussed.

Effects of Long-Term Organic Amendments on Soil Organic Carbon in a Paddy Field: A Case Study on Red Soil

Soil organic carbon （SOC） is one of the main carbon reservoirs in the terrestrial ecosystem. It is important to study SOC dynamics and effects of organic carbon amendments in paddy fields because of their vest expansion in south China. A study was carried out to evaluate the relationship between the SOC content and organic carbon input under various organic amendments at a long-term fertilization experiment that was established on a red soil under a double rice cropping system in 1981. The treatments included non-fertilization （CK）, nitrogen-phosphorus-potassium fertilization in early rice only （NPK）, green manure （Astragalus sinicus L.） in early rice only （OM1）, high rate of green manure in early rice only （OM2）, combined green manure in early rice and farmyard manure in late rice （OM3）, combined green manure in early rice, farmyard manure in late rice and rice straw mulching in winter （OM4）, combined green manure in early rice and rice straw mulching in winter （OMS）. Our data showed that the SOC content was the highest under OM3 and OM4, followed by OM1, OM2 and OM5, then NPK fertilization, and the lowest under non-fertilization. However, our analyses in SOC stock indicated a significant difference between OM3 （33.9 t ha^-1） and OM4 （31.8 t ha^-1）, but no difference between NPK fertilization （27 t ha^-1） and nonfertilization （28.1 t ha^-1）. There was a significant linear increase in SOC over time for all treatments, and the slop of linear equation was greater in organic manure treatments （0.276-0.344 g kg-1 yr^-1） than in chemical fertilizer （0.216 g kg^-1 yr^-1） and no fertilizer （0.127 g kg^-1 yr^-1）.

Effect of Different Amendments on Ryegrass Growth in Copper Mine Tailings

Montmorillonite, rice straw, organic manure and chemical fertilizer were usedas amendment materials for copper mine tailings, and their effects on mine tailing pH, nutrientsarid metal availability to ryegrass were investigated. Chemical fertilization was the most effectiveone in improving ryegrass growth in mine tailings among the amendment materials examined. It wasfound that montmorillonite raised biomass of ryegrass at the 1st and 2nd cuts, but it did not givefurther positive effects at the3rd and 4th cuts. The effect of organic materials on ryegrass growthwas not so good as expected, mainly due to their slow decomposition in mine tailings with less soilmicroorganisms. Available Cu and Zn contents in mine tailings decreased in the presence ofmontmorillonite but increased when rice straw and organic manure were used as amendments. Cu and Zncontents in ryegrass decreased with increasing the rate of montmorillonite application but increasedwith the rate of rice straw. Zn showed much stronger mobility from soil lo ryegrass than Cu, andalmost all the available N and P in mine tailings, except for the treatments with organic manure,were completely consumed after ryegrass had grown in mine tailings for more than four months andbeen harvested for four times. Owing to its large biomass and high metal uptake, ryegrass is apotential plant for remediation of metal contaminated soils in practice.

Effectiveness and longevity of amendments to a cadmium-contaminated soil

The effectiveness and longevity of amendments will influence the reduction in cadmium(Cd) bioavailability by in situ remediation techniques. Different amendments, including red mud(RM), corn straw(CS), rape straw(RS), and their combinations with zinc(Zn) fertilizer, were evaluated based on a long-term field experiment. It was found that all amendments decreased the concentration of available-Cd(EDTA-Cd and Exch-Cd) in soil and also reduced the Cd content(%) in plants. The amendments were still effective after eight years, although the effect did decline over time. The reduction of plant Cd content was 83.5% for red mud plus rape straw(RMRS), 65.3% for red mud plus corn straw(RMCS), 50.9% for RS, 54.0% for RM, and 37.3% for CS in the first few years. The reduction in plant Cd content was still 17.2% for RMRS after eight years, and RMRS was found to be the most effective treatment for decreasing Cd bioavailability. This study also explained that why the reduction in plant Cd content declined over time is the change of available Cd content in soil over time, which is important for guiding agricultural practice. It was concluded that RM, CS, RS, and their combinations with Zn fertilizer as effective amendments can have a profound and lasting positive impact on Cd-contaminated soils.

Relative Effectiveness of Various Amendments in Improving Yield and Nutrient Uptake under Organic Crop Production

In organic farming, artificial/synthetic inorganic fertilizers/chemicals are not applied to increase crop yields, but adequate amounts of nutrients are essential for sustainable high production from agricultural crops. Two 3-year (2008 - wheat, 2009 – pea, and 2010 - barley) field experiments were conducted on certified organic farms near Spalding (Dark Brown Chernozem – Typic Haploboroll) and Star City (Gray Luvisol – Typic Haplocryalf) in northeastern Saskatche-wan to determine the relative effectiveness of various organic amendments (compost, alfalfa pellets, wood ash, rock phosphate, Penicillium bilaiae, MykePro, or gypsum), and intercropping of non-legume (wheat, barley) and legume (pea) annual crops on seed yield, total biomass yield (TBY) and nutrient uptake in seed + straw of wheat, pea and barley. In 2008, seed yield, TBY and nutrient uptake of wheat increased (but small) with compost and alfalfa pellets. In 2010, seed yield, TBY and nutrient uptake of barley increased substantially with compost and alfalfa pellets and moderately with wood ash. Other amendments had little or no effect on crop yield and nutrient uptake. In 2009, there was no beneficial effect of any amendment on yield and nutrient uptake of pea, most likely due to fixation of N which is the most limiting nutrient in these soils. Intercropping of wheat or barley with pea produced greater seed yield and nutrient uptake per unit land area basis compared to wheat or barley grown as sole crops in most cases. In conclusion, our results suggest potential benefits in improving yield and nutrient uptake of wheat and barley from compost, alfalfa pellets and possibly wood ash, most likely by preventing deficiencies of some nutrients, especially N, lacking in these soils under organic farming. Our findings also suggest the need for future research to determine the feasibility of rock phosphate, Penicillium bilaiae, MykePro, gypsum or other amendments in preventing P and/or S deficiency in organic crops using soils extremely deficient in these nutrients.

Feasibility of Rock Phosphate and Other Amendments in Preventing P Deficiency in Barley on a P-Deficient Soil in Northeastern Saskatchewan

In?the Canadian Prairies, many soils on organic farms are low in available P, and the only alternative is to use external sources to prevent P nutrient deficiency on these soils. A 3-year (2012 to 2014) field experiment was established in spring 2012 on a P-deficient soil near Kelvington, Saskatchewan, Canada, to determine the potential of organic amendments (alfalfa pellets, compost manure, thin stillage and distiller grain dry of wheat), inorganic amendments (rock phosphate granular, rock phosphate fine, wood ash and bone meal ash) and microbial inoculants/products (JumpStart&reg;and MYKE&reg;PRO), applied alone or in a combination with N and/or P commercial fertilizers, in preventing P deficiency and increasing seed yield, N and P uptake of barley. Compared to unfertilized control, N only treatment did not result in any significant increase in seed yield, while application of P alone increased seed yield significantly but to a lesser degree than when both N and P fertilizers were applied together in all 3 years. Rock phosphate did not result in any seed yield benefit, even when applied along with N fertilizer. Wood ash fine increased seed yield of barley significantly only in the presence of N fertilizer, with highest seed yield in the presence of both N + P fertilizers. Seed yield of barley increased moderately with alfalfa pellets, significantly with compost manure, and considerably with distiller grain dry of wheat, but highest seed yield was obtained from thin stillage, which was essentially similar to that obtained from the N + P fertilizer combination. There was no yield benefit from JumpStart or MykePro in any year and only slight benefit from bone meal ash in 2013. The addition of N fertilizer to MykePro or bone meal ash treatments increased seed yield, but highest yield was obtained when both N and P fertilizers were added, suggesting a lack of available P for optimum seed yield. With few exceptions, the response trends of total N and P uptake in seed + straw to the amendments studied were generally similar to those of seed yield. In conclusion, the organic amendment “thin stillage” provided balanced nutrition and produced yield and nutrient uptake of barley similar to balanced N + P fertilizer treatment, and it was closely followed by “distiller grain dry of wheat”, with moderate benefit from compost manure and some benefit from alfalfa pellets. In this extremely P-deficient soil, rock phosphate was not found effective in preventing P deficiency in barley, while wood ash and bone meal ash provided moderate increase in barley yield, with little yield benefit from JumpStart and MykePro, when other nutrients were not limiting in the soil.

Soil organic matter amendments in date palm groves of the Middle Eastern and North African region:a mini-review

Countries in the Middle Eastern and North African (MENA) region are among the most water-scarce regions in the world, and their dryland soils are usually poor in organic carbon content (<0.5%). In this study, we summarize examples of how people in the few oases of the MENA region overcome environmental challenges by sustainably managing economically important date production. On the basis of the limited studies found in the existing literature, this mini-review focuses on the role of traditional soil organic matter amendments beneath the soil surface as a key tool in land restoration. We conclude that soil organic matter amendments can be very successful in restoring soil water and preventing the soil from salinization.

Soil Macrofauna Behaviour in the Presence of Pesticides and Organic Amendments

Insects attack vegetable crop, leading to an overuse of pesticides. Organic amendments are recommended to increase soil fertility. The impact of two insecticides, on soil macrofauna under rainfed cultivation of tomato (Lycopersicon esculentum L.) with or without organic amendments was evaluated. The insecticides were Lambda Super (lambda-cyhalothrin) and Dursban (chlorpyrifos ethyl) and organic amendments were compost, pig manure and cattle manure. An experimental device in split-plot with three replicate was installed. Pesticides were applied periodically each week during the experiment. The results have showed that with organic amendments, Lambda super increased the earthworm population compared to the control. Indeed, we found 42 individuals/m2 with compost;1 individuals/m2 with pig manure and 27 individuals/m2 with cattle manure but the control was 0 individuals/m2 in the presence of Lambda super without organic amendment. Similarly, Dursban increased the population of earthworms in the presence of organic amendment with 11, 37 and 91 individuals/m2 respectively for compost, pig manure and cattle manure. Lambda super with compost has led to a total elimination of termites. In the presence of Dursban, a decrease in the number of termites was observed when adding cattle manure (11 individuals/ m2) compared to the control containing only Dursban (21 individuals/m2). Better distribution of macrofauna was obtained with treatment with Dursban and compost (E = 0.99 for earthworms and E = 0.96 for termites). All organic amendments used in our study stimulated earthworm population, but more in the presence of Lambda super or Dursban.

Assessing Effects of Crop History and Soil Amendments on Yields of Subsequent Crops

Three field trials were set up to measure the effect of previous crops or soil amendments on the yields of subsequent crops of cereals under a cool temperate maritime climate in arable crop land in the east of Scotland. Winter wheat and winter barley direct drilled into legume and cereal + legume stubble (pre-crop) gave substantial yield boost compared with other pre-crop cereals, but pre-crop effects of oats were similarly great. Restored rotation after continuous barley gave expected yield enhancement to subsequent winter and spring barley but not to subsequent wheat. Some diseases were reduced on restored rotation crops. Slurry effects on yield were generally small but beneficial and compost effects were greater. However, compost had effects on plant developmental speed and was difficult to compare directly with other treatments. NDRE measurements in the restored rotation and soil amendment trials indicated that yield gains were associated with improved crop health as indicated by leaf chlorophyll content. There were no clear cultivar interactions within crop type with treatments effects in any of these trials.

Apatite and Chitin Amendments Promote Microbial Activity and Augment Metal Removal in Marine Sediments

In situ amendments are a promising approach to enhance removal of metal contaminants from diverse environments including soil, groundwater and sediments. Apatite and chitin were selected and tested for copper, chromium, and zinc metal removal in marine sediment samples. Microbiological, molecular biological and chemical analyses were applied to investigate the role of these amendments in metal immobilization processes. Both apatite and chitin promoted microbial growth. These amendments induced corresponding bacterial groups including sulfide producers, iron reducers, and phosphate solubilizers;all that facilitated heavy metal immobilization and removal from marine sediments. Molecular biological approaches showed chitin greatly induced microbial population shifts in sediments and overlying water: chitin only, or chitin with apatite induced growth of bacterial groups such as Acidobacteria, Betaproteobacteria, Epsilonproteobacteria, Firmicutes, Planctomycetes, Rhodospirillaceae, Spirochaetes, and Verrucomicrobia;whereas these bacteria were not present in the control. Community structures were also altered under treatments with increase of relative abundance of Deltaproteobacteria and decrease of Actinobacteria, Alphaproteobacteria, and Nitrospirae. Many ?of these groups of bacteria have been shown to be involved in metal reduction and immobilization. Chemical analysis ?of pore and overlying water also demonstrated metal immobilization primarily under chitin treatments. X-Ray absorption spectroscopy (XAS) spectra showed more sorbed Zn occurred over time in both apatite and chitin treatments (from 9% - 27%). The amendments improved zinc immobilization in marine sediments that led to significant changes in ??the mineralogy: easily mobile Zn hydroxide phase was converted to an immobile Zn phosphate (hopeite). In-situ amendment of apatite and chitin offers a great bioremediation potential for marine sediments contaminated with heavy metals.

Short-term residual effects of various amendments on organic C and N, and available nutrients in soil under organic crop production

Two 3-year (2008-2010, wheat-pea-barley) field experiments were conducted on certified organic farms near Spalding (Dark Brown Chernozem-Typic Haploboroll) and Star City (Gray Luvisol-Typic Haplocryalf) in northeastern Sas-katchewan, Canada, to determine the residual effects of compost, alfalfa pellets, wood ash, rock phosphate, Penicillium bilaiae, gypsum and MykePro on organic C and N (total organic C [TOC], total organic N [TON], light fraction organic C [LFOC], light fraction organic N [LFON]) and mineralizable N (Nmin) in the 0 - 15 cm soil layer, and ammonium-N, nitrate-N, extractable P, exchangeable K and sulphate-S in the 0 - 15, 15 - 30 and 30 - 60 cm soil layers in autumn 2010. Compared to the unamended control, mass of TOC, TON, LFOC and LFON increased with compost and alfalfa pellets in both soils. However, the increases were much more pronounced for LFOC (by 125% - 133%) or LFON (by 102% - 103%) than TOC (by 19% - 29%) or TON (by 25% - 40%). The Nmin also increased in these two treatments compared to the control, but the increases were much smaller for compost than alfalfa pellets. In general, residual nitrate-N increased with increasing rate of compost and alfalfa pellets in the 0 - 15 and 15 - 30 cm layers in both soils. Extractable P increased with compost and exchangeable K with alfalfa pellets, but only in the 0 - 15 cm soil layer. Sulphate-S increased with compost, but mainly in the 30 - 60 cm soil layer. Soil pH usually increased with compost and more so with wood ash, but no effect of any amendment on ammonium-N. Overall, the quantity of organic C and N, and available nutrients in soil increased with compost and/or alfalfa pellets, but the magnitude varied with amendment and/or soil type. In conclusion, our findings suggest that soil quality and fertility can be improved with these organic amendments, suggesting sustainability of production from organic crops.

Application of Soil Amendments Reduced Cadmium Bioavailability but Restrained Soybean Growth

The soybean is a crop which easily accumulates cadmium(Cd),which threatens human health.To assess the impact of the application of classic soil amendments on the Cd concentration in the soybean and the Cd bioavailability in the soil,a field study was conducted in Xiangtan Country(XT)and Liling City(LL),with inorganic-organic-microbial matter(T1)and silicon-calcium-magnesium oxide from natural minerals(T2)as two soil amendments in this study.The results indicated that the soil pH in the two sites increased significantly,up to 0.7~1.1 units and the Cd concentration in the stem,leaf,husk and seed in the two sites decreased differently.Of which,the soil available Cd in Xiangtan County(XT)decreased by 11.9%~16.0%,the enrichment factor(EF)and translocation factor(TF)reduced by 37.9%and 23.5%,respectively.Both soil amendments were effective in increasing the soil pH,reducing the seed and soil available Cd,but the soil organic matter,total N,stem length and grain yields decreased slightly.In conclusion,the Cd bioavailability was reduced but the soybean growth was restrained with the application of the soil amendments.