Green Manure Amendment Research Articles

Relationships between yield of winter wheat and bacterial and protozoan fatty acids affected by different green manure amendments

ABSTRACT Soil microorganisms play important roles in crop growth and nutrient cycling. This study investigated the influence of the temporal changes in soil fatty acids (FAs) mainly derived from microorganisms by the incorporation of different green manures on the subsequent crop yield of winter wheat. Plants (Sesbania rostrata or Sorghum bicolor) as green manure were cultivated as the preceding crop, followed by the cultivation of winter wheat. Soil FA structure was characterized by the analysis of the relative abundance of FA methyl esters (FAMEs). Principal component (PC) analysis of the abundance of FAME signatures indicated that the composition of soil FAs was clearly altered by different soil management regimes. The amount of soil FAMEs increased with the incorporation of green manure, and this increase was maintained during wheat cultivation. A positive correlation was observed between wheat yield and the ratio of FAMEs derived from Gram-positive and Gram-negative bacteria at stages of tiller emergence and heading. FAMEs from Gram-positive bacteria and protozoa also positively correlated with one of the wheat yield components, 1,000 grain weight. These results may suggest that the amount of bacterial and protozoan FAs at tiller and heading stage following green manure incorporation is useful to predict the winter wheat productivity.

Short term effects of different green manure amendments on the composition of main microbial groups and microbial activity of a submerged rice cropping system

Green manuring is a feasible agricultural practice to mitigate soil degradation and loss of biodiversity caused by long term application of inorganic fertilizer. However, the effect of the types of green manure (legume vs non-legume) on soil microbial groups and activities are largely not known. Field experiments were conducted to investigate the effects of incorporating two green manures that originated from residues of barley (Hordeum vulgare) and hairy vetch (Vicia villosa), on microbial groups, biomass, enzyme activities, nutrient availability of soil, and crop yield in a mono-rice cropping system. Green manure biomasses were applied on an equal nitrogen biomass basis. We found that, compared to inorganic fertilizer, green manures amendment significantly increased composition of main microbial groups, microbial biomass C (MBC) and hydrolase activities of soil. Total PLFAs, Gm + bacteria, fungi and actinomycetes PLFAs were markedly increased by the barley residue amendment, whereas Gm- bacteria PLFA was mostly increased by the hairy vetch residue amendment. The higher hydrolase activities involved in C cycling were observed in the barley treatments, whereas soil enzyme activities involved in N and P cycling were higher in the hairy vetch treatments. Probably, differences between the two treatments dependent on different chemical composition of the green manures incorporated into the soil and their mineralization controlled by the soil C:N ratio. A decrease in oxidative enzyme activities and higher fungi: bacteria ratio as a result of the green manure amendment, in particular barley, suggested the potential of barley biomass incorporation to enhance C storage in submerged rice cropping systems.

Impacts of green manure amendment on detritus micro-food web in a double-rice cropping system

Chinese milk vetch (CMV) is widely used as a green manure due to its efficiency for nutrient preservation and soil fertility improvement, as well for providing more organic substances for soil organisms. Detritus micro-food web drives carbon and nutrient cycling and maintains ecosystem productivity. The effects of CMV amendment on detritus micro-food web were investigated in a six-year field experiment. Compared to the mineral fertilizers (NPK) alone, the fertilizers combined with CMV (NPK + CMV) increased soil organic carbon content, and thus enhanced the biomass of microorganisms, as well as protozoa abundance, while did not change micro-feeding nematode abundance (MN). This indicates a substrate-driven bottom-up effect. However, the green manure application increased omnivores-predators (OP) abundance and the OP/MN ratio, suggesting a top-down effect. Higher F/B ratio indicates a shift of the food web energy structure towards to fungi-dominated channel in the manured soil. Here, the green manure amendment should be encouraged to improve soil detritus micro-food web.

Green manure amendment enhances microbial activity and diversity in antibiotic-contaminated soil

The impacts of antibiotics on soil microbial activity and community structure are poorly understood. It is also important to identify strategies to reduce the problems that antibiotics inflict on soil biology. Hence, for the first time, this study investigated the effect of sulfathiazole (STZ) on soil microbial activity (measured in terms of dehydrogenase activity) and bacterial community structure (revealed by pyrosequencing analysis) in antibiotics contaminated soils (10 and 100 mg STZ kg−1 soil), and treated with (in)organic amendments (NPK, compost and hairy vetch). Dehydrogenase activity was significantly higher in the hairy vetch amended soils (with and without STZ). Pyrosequencing analysis revealed a concentration dependent impact of antibiotics on soil microbial richness and diversity. Proteobacteria and Actinobacteria were present in greater proportions even in soils with a high antibiotic concentration of 100 mg kg−1. With 10 mg kg−1 STZ, the effect on microbial community richness and diversity was minimal. Meanwhile, with 100 mg kg−1 STZ, the disappearance of Verrucomicrobia, Bacteroidetes and Planctomycetes was observed. Even with a high antibiotic spiking concentration, a tremendous increase in the relative abundance of Firmicutes was seen in the hairy vetch amended soils which led to a considerably higher Gram-positive proportion than the compost and NPK treatments. We conclude that utilization of green manure (cover crop – hairy vetch) can be considered a viable strategy for safer crop production in antibiotic-contaminated soils. This is because it enhances soil microbial/enzyme activity, bacterial richness and diversity, notably the population of beneficial Gram-positive bacteria.

Effect of green manure amendment on herbicide pendimethalin on soil

ABSTRACTManure amendment in agricultural practice can have a large effect on herbicide dissipation because the period of manure plowing is close to the period of herbicide application. In addition, manure amendment is among the frequently encountered options in ameliorating pesticide pollution. In this research, the dissipation of the herbicide pendimethalin was examined after amendment with two common green manures, Lupinus luteus (L) or Cosmos bipinnatus (C), for 110 days in pH 5.2 and 7.7 soils (Sankengtzu [Sk] and Erhlin [Eh] soil, respectively). The microbial activity and ecology changes were examined by using Biolog EcoPlate and denaturing gradient gel electrophoresis (DGGE). In Sk soil, the half-lives of pendimethalin with L, C, and blank treatment were 49.0, 54.9, and 62.2 days, respectively, whereas that in Eh soil they were 46.3, 52.6, and 34.8 days, respectively. Pendimethalin dissipated quickly in more neutral soil (Eh soil), but the addition of manure can only increase the dissipation rate in acidic soil (Sk soil), indicating that the amendment of manures exerted different effect in pendimethalin dissipation rates in different pH soils. The application of pendimethalin and/or manure altered the microbial community activity after 24 h of incubation. After 110 days, the microbial community activities in green manure–amended soil were more similar to that with blank than pendimethalin treatment in both types of soils. In comparison with treatment C, microbial communities were more similar between treatment L and blank, indicating the superior effect over pendimethalin on microbial communities when applying Lupinus luteus. The research showed that the application of herbicide pendimethalin changed soil microbial community, and the amendment of manures exerted different effect in pendimethalin dissipation rates in different pH soils. It is assumed that the change in dissipation rates was originated from the microbial community change after different manure amendment.

Potential role of compost and green manure amendment to mitigate soil GHGs emissions in Mediterranean drip irrigated maize production systems

Organic fertilization can preserve soil organic matter (SOM) and is foreseen as an effective strategy to reduce green house gases (GHGs) emissions in agriculture. However, its effectiveness needs to be clarified under specific climate, crop management and soil characteristics. A field experiment was carried out in a Mediterranean drip irrigated maize system to assess the pattern of soil CO2 and N2O fluxes in response to the replacement of a typical bare fallow–maize cycle under urea fertilization (130 kg N ha−1 y−1) (CONV) with: (i) bare fallow-maize cycles under two doses of compost (COM1 and COM2, 130 and 260 kg N ha−1 y−1, respectively) and (ii) a vetch-maize cycle, with vetch incorporation as green manure (130 kg N ha−1 y−1) (GMAN).Along the maize period (MP), reduced daily N2O emissions were detected in organic treated soils compared to CONV, mainly in the first stages of the cultivation, thanks to the slow release of available nitrogen from the organic substrates. Cumulative N2O fluxes (kg N2O-N ha−1) in MP scored to 0.24, 0.14, 0.12 and 0.085 for CONV, COM1, COM2 and GMAN, respectively, with significantly lower emissions in GMAN respect to CONV. CO2 fluxes partially reflected the ranking observed for maize yields, with cumulated values (Mg CO2-C ha−1) of 2.2, 1.5, 2.1, 2.1 for CONV, COM1, COM2 and GMAN, respectively, and significantly lower in COM1 respect to the other treatments.During the fallow period (FP), compared to CONV (0.77 Mg CO2-C ha−1 and 0.25 kg N2O-N ha−1), enhanced GHG fluxes were detected in COM treatments (about 0.90 Mg CO2-C ha−1 and 0.37 kg N2O-N ha−1, as averaged values from COM1 and COM2), likely driven by the slow prolonged mineralization of the added organic matter. GMAN showed comparable CO2 (0.82 Mg CO2-C ha−1) and N2O emissions (0.30 kg N2O-N ha−1), in consequence of restrained post-harvest residual N coupled with the counteracting effect of vetch uptake.Respect to the total yearly GHG emissions in CONV (about 194 kg CO2 eq ha−1 y−1), the overall results showed commensurate slightly higher GWP in COM treatments (+11% as averaged value from COM1 and COM2). The yield-scaled global warming potential (GWP) resulted 60% higher and nearly doubled for COM2 and COM1 respectively, according to the lower COM yields, markedly dampening at halved compost dose. GMAN appeared the best performing organic treatment, with lower GWP (−27%) and competitive yields respect to CONV.All treatments showed N2O emission factors consistently lower compared with the default IPCC 1% value.

Adverse effects of brassica green manures on encysted eggs, infective second-stage juveniles and the reproduction of Globodera rostochiensis

Potato cyst nematodes (PCN), Globodera spp., are major pests of potato worldwide. In this study, the toxicity of an aqueous extract (1 g/ml) of fresh leaves of brassica species (savoy cabbage, cauliflower, broccoli, red cabbage, turnip, white mustard and edible radish) was tested on G. rostochiensis encysted eggs and infective, second-stage juveniles (J2) in vitro. Soil infested with cysts (Pi 20 eggs/g soil) was either fumigated with metham sodium and/or biofumigated with 2 % green manure of brassica and wheat under glasshouse conditions. More than 99 % of the J2 were paralysed after 24 h and <1 % of J2 hatched from encysted eggs during a 6-week exposure to brassica extracts. Nematode reproduction on the susceptible potato cv. Marfona was reduced by green manure amendments, the numbers of new cysts was reduced by between 60 % in radish- and 33 % in cauliflower-treated soil. The reproduction rate of G. rostochiensis was reduced to less than 1, and final populations of eggs and J2/g soil were reduced by between 73 % (white mustard) and 92 % (edible radish). Likewise, green manure of wheat and metham sodium fumigation decreased potato cyst nematode reproduction rates to below one, new cysts by 50 and 42 %, and final eggs/g soil by 81 and 88 %, respectively. In infested soil, total fresh weight of aerial parts and roots of potato was decreased by 64 %, while total weight of plants was increased between 21 and 74 % in brassica amended soil, and 56 and 76 % in wheat and metham sodium-treated soil, respectively.

The effect of green manure and organic amendments on potato yield, nitrogen uptake and soil mineral nitrogen

Fertility management is challenging for organic crops with intensive nutrient demands such as potatoes (Solanum tuberosum L.). Four crop sequences varying in pre-potato green manures as main plots and four fertility treatments applied in the potato phase only [control, inorganic fertilizer (FERT), municipal solid food waste compost (MSW) and paper mill biosolid compost (PMB)] as subplots were compared in five-year organic potato rotations in Eastern Canada. Potato yields did not differ significantly between crop rotations; however, soil amendments had significant impacts on potato yields. Averaged across years, total tuber yields were in the order; FERT (34.2 Mg ha−1) > MSW (29.6 Mg ha−1) > control (26.5 Mg ha−1). Total potato N uptake (TNU) levels were 89, 115, 107 and 147 kg N ha−1, respectively, for control, MSW, PMB and FERT, and were greater when potato followed red clover (119–124 kg N ha−1) compared with oat/pea/vetch mixture (107–108 kg N ha−1). Plant N use efficiency (NUE) was 299, 263, 263 and 235, respectively, for control, MSW, PMB and FERT. Pre-plant soil mineral N (SMN) ranged between 39 and 112 kg N ha−1 among different crop rotations. During the tuber initiation stage, SMN ranged between 40 and 66 kg N ha−1 while during tuber bulking it ranged between 10 and 14 kg N ha−1 among different crop rotations and soil amendments. Post-harvest SMN ranged between 8 and 30 kg N ha−1 for all rotations and amendment treatments.

Survival reduction of Phytophthora capsici oospores and P. nicotianae chlamydospores with Brassica green manures combined with solarization

Phytophthora capsici and Phytophthora nicotianae are the main soil-borne pathogens of greenhouse sweet pepper in Southeast (Murcia) and P. nicotianae of open field paprika pepper crops in West (Extremadura) of Spain. Both oomycete cause plant root rot. The effects of green manure amendment (Brassica carinata, Brassica nigra, Sinapis alba, non-amended as control), transparent plastic tarp (non-tarped=biofumigation, tarped=biosolarization) and depth (15cm, 30cm) were assessed for the survival of P. capsici oospores and P. nicotianae chlamydospores in two consecutive years. In Murcia, biosolarization for six weeks significantly reduced the viability of oospores (values for the two soil depths ranged from 4.0–12.2% viables in biosolarized soil to 21.2–26.0% in non-treated soil in 2010 and from 6.9–31.1% to 52.4–54.9% in 2011) and the infectivity of oospores (values for the two soil depths and the two years ranged from 0.0–11.1% of diseased plants in biosolarized soil to 8.3–44.4% in non-treated soil) and chlamydospores (0.0% to 0.0–11.1%). The reduction of inoculum viability was greater with S. alba and B. nigra (6.6 and 5.7% of viable oospores) than with B. carinata (18.9%) and higher than in the non-treated soil (21.2%). Despite the low soil temperatures in Extremadura (15–29°C), S. alba further reduced chlamydospore infectivity when compared to B. nigra or non-amended soil in the second year (29.2, 52.1 and 45.9% of diseased plants respectively). Biosolarization with brassicas can be recognized as an effective method to reduce Phytophthora survival in soils of greenhouse pepper crops of Murcia and with better effects on infectivity of inoculum of P. nicotianae (0.0% diseased plants) than on P. capsici (0.0–11.1% diseased plants). Conversely, the results in Extremadura were not sufficiently consistent in the two year experiment thus, this procedure cannot be recommended for Phytophthora control in Extremadura open field.

Brassica Green Manure Amendments for Management of Rhizoctonia solani in Two Annual Ornamental Crops in the Field

Brassica green manure soil amendments are a possible alternative to chemical management of soilborne diseases of ornamental landscape and bedding plants. The objective of this study was to determine the importance of crop selection and application rate of brassica green manures for disease caused by Rhizoctonia solani on impatiens and petunia. Microplot experiments were conducted over 2 years using brassica green manure soil amendments for R. solani management of both petunias and impatiens. Brassica crops used were Brassica juncea ‘Fumus’ and ‘Bionute’, and Brassica napus ‘Jetton’, at the application rates of 700, 1400, and 4200 g·m−2 fresh weight aboveground biomass. Microplots were artificially infested to evaluate disease on these ornamentals, with a second set of experiments using noninfested plots to examine effects of the green manure alone on plant growth. All brassica green manure crops reduced disease symptoms in both impatiens and petunias. Rate of brassica application was more important than brassica crop variety for use as a green manure. The highest rate of the brassica green manure decreased crown lesions by 21% and 24%, root discoloration by 9% and 7%, and R. solani isolation by 15% and 8% for impatiens and petunias, respectively, for 4200 g·m−2 compared with 700 g·m−2 rates of application. No phytotoxic effects were observed from the brassica green manures following a waiting period of 4 weeks between amending the soil and planting the ornamental crops.

Effect of green manure and supplemental fertility amendments on selected soil quality parameters in an organic potato rotation in Eastern Canada

The effects of green manure, crop sequence and off-farm composts on selected soil quality parameters were assessed in a three-year organic potato (Solanum tuberosum L.) rotation in Eastern Canada. Three crop sequences varying in preceding green manure [red clover (RCl) + RCl, and beans/buckwheat or carrots + oats/peas/vetch mixture (OPV)] as main plots and four fertility treatments applied in the potato phase only [control; inorganic fertilizer; municipal solid waste compost (MSW); composted paper mill biosolid (PMB)] as subplots were compared. In 2008 and 2010, changes in selected soil quality parameters (0–15 cm) were assessed prior to planting of potatoes and at potato tuber initiation stage. Potentially mineralizable nitrogen (N) and the acid phosphatase enzyme activity average values across years were greater following RCl (1.51 abs and 622 kg ha−1) compared with OPV (1.32 abs and 414 kg ha−1) at potato planting. Soil NO3–N average value was greater following RCl compared with OPV (63 vs. 52 kg ha−1) at tuber initiation. For the other measured parameters, OPV and RCl were similar. The soil organic carbon (C) and particulate organic matter-C were greater under PMB and MSW (31.1 and 7.57 kg ha−1) compared with fertilizer treatment (27.9 and 6.05 kg ha−1). The microbial biomass C and microbial biomass quotient were greater under MSW (216 kg ha−1 and 0.73 %) than PMB and fertilizer (147 kg ha−1 and 0.50 %) across crop rotations. Annual legume green manures and off-farm composts can be used to satisfy potato N requirement and maintains soil quality in organic potato rotations.

Green manure addition to soil increases grain zinc concentration in bread wheat.

Zinc (Zn) deficiency is a major problem for many people living on wheat-based diets. Here, we explored whether addition of green manure of red clover and sunflower to a calcareous soil or inoculating a non-indigenous arbuscular mycorrhizal fungal (AMF) strain may increase grain Zn concentration in bread wheat. For this purpose we performed a multifactorial pot experiment, in which the effects of two green manures (red clover, sunflower), ZnSO4 application, soil γ-irradiation (elimination of naturally occurring AMF), and AMF inoculation were tested. Both green manures were labeled with 65Zn radiotracer to record the Zn recoveries in the aboveground plant biomass. Application of ZnSO4 fertilizer increased grain Zn concentration from 20 to 39 mg Zn kg−1 and sole addition of green manure of sunflower to soil raised grain Zn concentration to 31 mg Zn kg−1. Adding the two together to soil increased grain Zn concentration even further to 54 mg Zn kg−1. Mixing green manure of sunflower to soil mobilized additional 48 µg Zn (kg soil)−1 for transfer to the aboveground plant biomass, compared to the total of 132 µg Zn (kg soil)−1 taken up from plain soil when neither green manure nor ZnSO4 were applied. Green manure amendments to soil also raised the DTPA-extractable Zn in soil. Inoculating a non-indigenous AMF did not increase plant Zn uptake. The study thus showed that organic matter amendments to soil can contribute to a better utilization of naturally stocked soil micronutrients, and thereby reduce any need for major external inputs.

Effect of Rapeseed Green Manure Amendment on Soil Properties and Rice Productivity

Green manure crops can be used as alternatives to mineral fertilizers because they improve soil structure and nutrient content of soil. Here, we evaluated the effect of partial replacement of mineral nitrogen (N) fertilizer with rapeseed residue green manure on soil properties and rice productivity in a rice–rapeseed double-cropping system. The treatments were comprised of four levels of mineral N fertilizer and recommended levels of phosphate and potash fertilizers. Rice clum and panicle length did not differ between treatments. However, the proportion of ripened grains and 1,000-grain weight of rice plants were greater under rapeseed residue amendments than those under 100% conventional mineral N fertilizer treatments. Paddy soils treated with rapeseed residues had greater soil organic matter and exchangeable cations than those treated with mineral N fertilizer alone. Thus, rapeseed residues applied as green manure can serve as alternative N sources in sustainable rice–rapeseed double-cropping systems.

Evaluation of Green Manure Amendments for the Management of Fusarium Basal Rot (Fusarium oxysporumf.sp.cepae) on Shallot

Shallot (Allium cepaL. var.ascalonicum) is the most traditional vegetable crop in Ethiopia. Shallot is susceptible to a number of diseases that reduce yield and quality, among which fusarium basal rot (FBR) caused byFusarium oxysporumf.sp.cepae (Foc)is one of the most important yield limiting factors in Ethiopia. The present study was designed to evaluate the effectiveness ofBrassicacrops for the management of shallot FBR on shallot. The experiments were carried out at Debre Zeit Agricultural Research Center using cabbage (Brassica oleracea), garden cress (Lepidium sativum), Ethiopia mustard (B. carinata), and rapeseed (B. napus). The evaluations were done underin vitroand greenhouse conditions. Underin vitrotest condition it was confirmed that extracts of Ethiopian mustard and rapeseed showed higher inhibition on the growth ofFocpathogen compared to control. Data on seedling emergence, plant height, plant stand, disease incidence, severity, cull bulbs, and bulb weight were collected in greenhouse experiment. The green manure amendments of rapeseed and Ethiopian mustard significantly reduced disease incidence by 21% and 30% and disease severity by 23% and 29%, respectively. However the plant emergency was not significantly different among treatments in greenhouse test. These results indicated that Ethiopian mustard and rapeseed crops have potential as green manure for the management of FBR disease of shallot crop.

Sclerotium rolfsii dynamics in soil as affected by crop sequences

Crop rotation has been used for the management of soilborne diseases for centuries, but has not often been planned based on scientific knowledge. Our objective was to generate information on Sclerotium rolfsii dynamics under different crop or intercrop activities, and design and test a research approach where simple experiments and the use of models are combined to explore crop sequences that minimize Southern blight incidence.The effect of seventeen green manure (GM) amendments on sclerotia dynamics was analyzed in greenhouse and field plot experiments during two years. The relative densities of viable sclerotia 90 days after winter GM (WGM) incorporation were generally lower than after summer GM (SGM) incorporation, with average recovery values of 60% and 61% for WGM in the field, 66% and 43% for WGM in the greenhouse, and 162% to 91% for SGM in the greenhouse, in 2009 and 2010, respectively. Sclerotia survival on day d after GM amendment was described by the model Sf=Si×exp(−b×d), relating initial (Si) and final (Sf) sclerotia densities. Relative decay rates of the sclerotia (b) in SGM amended soil were largest for alfalfa (0.0077±0.0031day−1) and sudangrass (0.0072±0.0030day−1). In WGM amended soil, the largest b values were for oat (0.0096±0.0024day−1), wheat (0.0090±0.0024day−1) and alfalfa (0.0087±0.0023day−1).The effect of three cropping sequences (sweet pepper–fallow, sweet pepper–black oat and sweet pepper–onion) on sclerotia dynamics was analyzed in microplot experiments, and the data were used to calibrate the model Pf=Pi/(α+βPi), relating initial (Pi) and final (Pf) sclerotia densities. Median values for the relative rate of population increase at low Pi (1/α, dimension less) and the asymptote (1/β, number of viable sclerotia in 100g of dry soil) were 8.22 and 4.17 for black oat (BO), 1.13 and 8.64 for onion (O), and 6.26 and 17.93 for sweet pepper (SwP).By concatenating the two models, sclerotia population dynamics under several crop sequences were simulated. At steady state, the sequence SwP–O–Fallow–BO resulted in the lowest long-term sclerotia density (7.09sclerotia/100g soil), and SwP–Fallow in the highest (17.89sclerotia/100g soil). The developed methodology facilitates the selection of a limited number of rotation options to be tested in farmers’ fields.

Seasonal variation of methane flux from coastal saline rice field with the application of different organic manures

A field experiment was conducted in an irrigated saline rice field of Gadakujang (a fishing hamlet of coastal Odisha, India, ravaged by the super cyclone of 1999 and cyclone BOB02 of 2006), to study the effects of locally available organic and fresh green manure amendment to the saline soil on methane (CH4) emission during wet and dry seasons using the conventional closed chamber flux measurement method. In a first report of this kind, CH4 emission vis-à-vis yield improvement of rice with different locally available organic manure application from coastal saline rice field soil of Odisha, is reported. The study confirms that CH4 flux from the saline soil planted to rice is significantly lower than that of irrigated inland non-saline rice field during both wet and dry seasons. Cumulative seasonal CH4 flux from different treatments of the coastal saline rice field ranged between 119.51 and 263.60 kg ha−1 during the wet season and 15.35–100.88 kg ha−1 during the dry season. Lower CH4 emission during the dry season may be attributed to the increased soil salinity (EC1:2) that went up from 0.76 dS m−1 during the wet season to 3.96 dS m−1 during the dry season. Annual CH4 emission per Mg grain yield was significantly low from plots treated with locally available green manure Morning glory (Ipomoea lacunosa) (17.27) with significantly high rice grain yield. Study indicates that Morning glory may be used as a potential green manure to increase grain yield and reduced CH4 emission from the coastal saline rice ecosystems of the tropics.

Manipulating Inoculum Densities of Verticillium dahliae and Pratylenchus penetrans with Green Manure Amendments and Solarization Influence Potato Yield

We used cover crops with demonstrated efficacy against Verticillium dahliae and Pratylenchus penetrans in combination with the biocidal practice of solarization to determine the importance of targeting both organisms for managing potato early dying, an issue relevant to the search for alternatives to soil fumigation. Two experiments were conducted in commercial fields using a split-plot design with cover crop treatments of rapeseed, marigold, forage pearl millet, sorghum-sudangrass, and corn as the main plot factor and solarization as the subplot factor. Cover crops were grown and solarization applied in year one, followed by potato in year two. The main effect of solarization was significant for reduced inoculum levels of both organisms in year two and increased tuber yields. The main effect of cover crop was also significant with lower population densities of P. penetrans following the marigold and millet treatments and of V. dahliae following rape and sorghum-sudangrass. The cover crop treatments influenced yield in only one of the experiments in the absence of solarization. The combinatorial effect of cover crops and solarization resulted in a wide range of pathogen population densities. Mean soil inoculum levels were negatively related to yield for V. dahliae in experiment 1, and for P. penetrans and the P. penetrans × V. dahliae interaction in both experiments.

Influence of Global Warming on Aggregate Stability and Hydraulic Conductivity Under Highland Soil Order in Turkey

Ongoing global warming may cause an increase in air and soil temperatures. These increases can then lead to increase in the frequency of soil freezing and thawing cycle during the winter in cooltemperate and other high-latitude regions. The purpose of this study was to explore the effects of repeated soil freezing and thawing treated cycles (FTTC) on wet aggregate stability (WAS) and hydraulic conductivity (HC) in incubation laboratory and field experiment on Pellustert, Argiustoll, Haplustept, and Fluvaquent soils, the major soil groups in the eastern part of Turkey. To provide long-term climatic effect of soil FTTC on WAS and HC, a laboratory study was conducted simulating with three steps based on 60-year temperature cycles occurring in the region. The results demonstrated that the initial WAS increased with increases in FTTC from 3 to 6, by 18% to 113% but decreased after that point in all the soil freeze-thaw treatments by 2% to 25%, depending on soil type. The effect was more pronounced with increased moisture contents at freezing. The percent decrease in HC of soils ranged from 19% to 44%. The highest WAS values of soil samples under laboratory condition were determined in the Argiustoll soil, followed by Pellustert 9 Haplustept 9 Fluvaquent but was Fluvaquent 9 Haplustept 9 Pellustert 9 Argiustoll for HC of the soils. The field study results showed that global climate changes occurring in recent decades in the region deeply affected the WAS and HC values and that the highland soils are most sensitive to the global climatic change. Increasing air temperature has resulted in the rise of soil temperature, increasing the frequency of soil freeze-thaw cycles during the winter in cool-temperature and other high-latitude regions. If ongoing global warming continues this trend, WAS and HC changes in highland soils may lead to decrease and alterations in regional agricultural production such that regular organic manure or green manure amendments will be needed to sustain soil management and crop production for these major soil groups.

Effect of mustard green manure and dried plant residue on chickpea wilt (Fusarium oxysporum f.sp. ciceris)

Pot experiments were carried out in the green house at Amhara Regional Agriculture Research Institute (ARARI) Bahirdar, Ethiopia, to evaluate the potential of Brassica carinata cultivars, namely Holleta-l, S-67 and Yellow Dodola in 2007 and 2008. The effect of B. carinata (Ethiopian mustard) cultivars Holleta-1, S-67 and Yellow Dodola as green manure and Holleta-1 as dried plant residue on chickpea fusarium wilt (Fusarium oxysporum f.sp. ciceris) was studied. Six rates of green manure and dried plant residue (0, 20, 40, 60, 80 and 100 g) each per kg of pathogen-infested soil were used in the experiments. Infested soil without B. carinata cultivars amendment as a control and susceptible check variety JG-62 without amendment was used in the experiments. In the experiments, the treatments were arranged in randomised complete block design in three replications and repeated twice. Data on seedling emergence, wilt incidence, fresh weight and dry weight were collected. The amendments of infested soil with B. carinata cultivars green manure and dried plant residue reduced the incidence of chickpea fusarium wilt. The incorporation of the green manure Holleta-1, S-67 and Yellow Dodola at 20–100 g/kg of infested soil was effective in reducing wilt incidences on chickpea. However, the incorporation of Yellow Dodola at 80 and 100 g green manure per kg of infested soil were the best combination in reducing significantly wilt incidence. The application of the dried plant residue at 20–100 g/kg of infested soil was effective in reducing wilt incidences on chickpea. However when applied dried plant residue at 60, 80 and 100 g green manure per kg of infested soil were better in reducing wilt incidence as compared to 20 and 40 g/kg of infested soil. The three cultivars green manure incorporated at different level of doses affected the influence of fusarium wilt on the fresh and dry weight respectively. The use of Holleta-1 green manure at 20–100 g/kg of infested soil significantly reduced disease incidence in the range of 20.0–33.3%. Green manure amendment S-67 significantly reduced disease incidence in the range of 20.0–46.6%. Yellow Dodola reduce disease incidence with 26.7–60%. The dried plant residue incorporated at different level influence fusarium wilt. The application of Holleta-1 dried plant residue at 20–100 g/kg of infested soil reduced disease incidence in the range 20.0–26.7%. The results imply the potential of using B. carinata green manure and dried plant residue as cultural management components in chickpea fusarium wilt disease management.

Effects of Biofertilizers Combined with Different Soil Amendments on Potted Rice Plants

This pot study investigated the effect of the combined application of two commercial biofertilizers viz. Biopower and EM (Effective Microorganisms) on rice (Oryza sativa L.) growth and yield in soils amended with farmyard manure, green manure, and NPK fertilizers. Biopower is a product of the Nuclear Institute for Biotechnology and Genetic Engineering (NIBGE), Pakistan, which contains species of associative and endophytic diazotrophs. EM (effective microorganisms), a product developed by Japanese scientists, consists of co-existing beneficial microorganisms, mainly species of photosynthetic and lactic acid bacteria, as well as yeast. Applying Biopower adversely affected plant growth and yield in NPK fertilizer amendment. Conversely, this biofertilizer markedly enhanced plant growth and yield in green manure amended soil while its effect was not significant in farmyard manure amendment. In green manure amendment, applying EM enhanced grain yield by 46%. Co-inoculation of Biopower and EM evidently improved root and shoot growth in farmyard manure amended soil. This study concludes that the two biofertilizers clearly enhanced shoot biomass and grain yield in green manure amended soils.