Nitrogen mineralization in a high altitude ecosystem in the mediterranean phytogeographical region of Turkey

Interrelations exist in the terrestrial ecosystems between the plant type and characteristics of nutrient uptake. Annual net nitrogen mineralization in soils of different plant communities in the high altitude zone of Spil mountain located in the Mediterranean phytogeographical region of Turkey was investigated throughout one year by field incubation method. Seasonal fluctuations resulting from field incubation were markedly higher in autumn and spring than summer. These are mainly associated with the changes in soil moisture being at minimum in the Mediterranean summer. A significant correlation was developed between the net Nitrate (kg NO3(-)-N ha week(-1)) production and soil water content (p<0.05; r = 0.316 in soil of 0-5 cm; r = 0.312 in soil of 5-15 cm). The results showed that the annual productivity of nitrogen mineralization shows different values depending on communities. Annual net ammonium (NH4(+)-N) production in the soils of each community was negatively estimated. However annual net nitrate (NO3(-)-N) production (0-15 cm) was higher in grassland (27.8 kg ha y(-1)) and shrub (25.0 kg ha y(-1)) than forest (12.4 kg ha y(-1)) community. While annual net N(min) values were close to each other in grassland (14.5 kg ha y(-1)) and shrub (14.1 kg ha y(-1)), but negative in forest community (-3.6 kg ha y(-1)). The reasons for these differences are discussed.     

Effect of sulphur and phosphorus on yield, quality and nutrient status of pigeonpea (Cajanus cajan)

A field experiment was conducted to study the impact of Sulphur(S) and Phosphorus (P) on yield, nutrient status of soil and their contents in pigeonpea (Cajanus cajan) during the year 2008-2009. Seven treatments were studied in Factorial Randomized Block Design with three replications. The treatment combinations were derived from three levels of sulphur (0, 20 and 40 kg S ha(-1)) and four levels of phosphorus (0, 25, 50 and 75 kg ha(-1)). The experimental soil was medium black, slightly calcareous, clay in texture and slightly alkaline in reaction. The results indicated a significant increase in grain yield (14.81 q ha(-1)) and straw yield (41.26 q ha(-1)) of pigeonpea after 20 kg S ha(-1) and 50 kg P2O5 ha(-1) treatment with common dose of nitrogen @ 30 kg ha(-1). The increase in grain and straw yield was 102.77 and 52.87% as compare to higher over control. Maximum number of pods plant(-1), maximum number of grains pod and test weight by this treatment was also observed as compared to control. Application of S and P improved soil fertility status and S alone did not influence P availability. Hence, in order to maintain the fertility status of the soil at high level, combine application of 20 kg S ha(-1) with 50 kg P2O5 ha(-1) is essential. The residual fertility status of soil is advocated for rainfed pigeonpea crop grown on vertisol in Vidarbha region.     

Biomonitoring insecticide pollution using non-target soil microarthropods

The scope of biomonitoring insecticide pollution in soil is discussed with the help of field and laboratory findings on the density, prey-predator ratio and fecundity of non-target microarthropod fauna. Field experiments were conducted in small plots with mustard, wheat and lady's finger crops and insecticides namely heptachlor 20EC (3.25 kg ai/ha = 16.25 lit/ha) and endosulfan 35EC (0.875 kg ai/ha = 2.5 lit/ha) applied at the seedling stages. Soil microarthropod population estimated at fortnightly intervals in the treated and untreated control plots revealed a general trend of adverse effect of the insecticides, prominently on the density and relative abundance of major prey groups like Collembola and Acari leading to notable decline in prey-predator ratio. Comparison of the percentage reductions of major taxonomic and trophic groups between pre-treatment and post-treatment intervals also demonstrated the ill effect of both heptachlor and endosulfan, notably on Collembola and the prey category. In the laboratory the survival success and fecundity of Cyphoderus javanus (Collembola) and Archegozetes longisetosus (Acari) were compared by exposing freshly emerged adults to sub-lethal concentrations of heptachlor and endosulfan for varying durations. The untreated control sets recorded high fecundity for both C. javanus and A. longisetosus, but chronic toxicity of the insecticides on adults confined to the treated soil resulted into very low fecundity. Even short duration exposure to heptachlor and endosulfan treated soil for 24 or 72 hours only was found to delay the egg-laying and decrease the fecundity of both the species. It is concluded that population responses and reproductive sensitivity in non-target soil microarthropods are potential eco-toxicological parameters for detecting pesticide pollution in soil and for ecological health assessment since the results are based on the bioactivity of toxicants.     

Nitrogen critical loads for alpine vegetation and terrestrial ecosystem response: are we there yet?

Increases in the deposition of anthropogenic nitrogen (N) have been linked to several terrestrial ecological changes, including soil biogeochemistry, plant stress susceptibility, and community diversity. Recognizing the need to identify sensitive indicators of biotic response to N deposition, we empirically estimated the N critical load for changes in alpine plant community composition and compared this with the estimated critical load for soil indicators of ecological change. We also measured the degree to which alpine vegetation may serve as a sink for anthropogenic N and how much plant sequestration is related to changes in species composition. We addressed these research goals by adding 20, 40, or 60 kg N x ha(-1) x yr(-1), along with an ambient control (6 kg N x ha(-1) x yr(-1) total deposition), to a species-rich alpine dry meadow for an eight-year period. Change in plant species composition associated with the treatments occurred within three years of the initiation of the experiment and were significant at all levels of N addition. Using individual species abundance changes and ordination scores, we estimated the N critical loads (total deposition) for (1) change in individual species to be 4 kg N x ha(-1) yr(-1) and (2) for overall community change to be 10 kg N x ha(-1) x yr(-1). In contrast, increases in NO3- leaching, soil solution inorganic NO3-, and net N nitrification occurred at levels above 20 kg N x ha(-1) x yr(-1). Increases in total aboveground biomass were modest and transient, occurring in only one of the three years measured. Vegetative uptake of N increased significantly, primarily as a result of increasing tissue N concentrations and biomass increases in subdominant species. Aboveground vegetative uptake of N accounted for <40% of the N added. The results of this experiment indicate that changes in vegetation composition will precede detectable changes in more traditionally used soil indicators of ecosystem responses to N deposition and that changes in species composition are probably ongoing in alpine dry meadows of the Front Range of the Colorado Rocky Mountains. Feedbacks to soil N cycling associated with changes in litter quality and species composition may result in only short-term increases in vegetation N pools.     

Distribution of organo-chlorine pesticides (DDT and HCH) between plant and soil system

This paper reports a study of the distribution of organo-chlorine pesticides (DDT and HCH) between rice plants and the soil system by spraying before the heading stage at four different dosage levels--control, normal dosage (15 kg ha(-1) of 6% HCH and 7.5 kg ha(-1) of 25% DDT), double dosage and four times dosage. Soil and plant samples were taken respectively at the 1st h, 3rd, 10th, 20th, and 40th day after spraying and at the harvest time. The results indicate that less than 5% of HCH and 15% of DDT were absorbed by the surface of rice leaves for normal dosage. Most of both pesticides moved into the soil in solution after spraying. Compared with DDT, HCH was degraded and run off more easily. HCH residues in the surface soil layer (1-3 cm) were already below 6.4 microg kg(-1) at the mature stage, lower than Chinese Environmental Quality Standard for Agricultural Soils: HCH < 0.05 mg kg(-1). However DDT residues in the surface soil layer remained 172 microg kg(-1), higher than the national standard: DDT < 0.05 mg kg(-1). According to the test f OCP residues in rice seeds, it can be concluded that the OCP sprayed onto the surface of rice leaves can move into rice plants and accumulate in the seeds at the mature stage. HCH residues in rice seeds of the double and four times dosage treatments, and DDT residues in all treatments, exceeded the Chinese National Food Standard (HCH < 0.10 mg kg(-1), DDT < 0.20 mg kg(-1)).     

Chemical changes in agricultural soils of Korea: data review and suggested countermeasures

The monitoring of chemical properties, including heavy metals, in soils is necessary if better management and remediation practices are to be established for polluted soils. The National Institute of Agricultural Science and Technology initiated a monitoring study that investigated fertility and heavy metal contents of the benchmarked soils. The study covered paddy soils, upland soils, and horticultural soils in the plastic film houses, and orchard soils throughout the Korea from 1990 to 1998. Likewise, 4047 samples of paddy and 2534 samples of plastic house in 1999 and 2000 were analyzed through the Soil Environment Conservation Act. Soil chemical properties such as pH, organic matter, available phosphate and extractable calcium, magnesium and potassium contents, and heavy metal contents such as cadmium, copper, lead, zinc, arsenic, mercury, and cobalt contents were analyzed. The study showed that the average contents of organic matter, available phosphate, and extractable potassium rapidly increased in plastic house soils than in upland or paddy soils. Two kinds of fertilizer recommendation systems were established for the study: the standard levels by national soil average data for 77 crops and the recommendation by soil test for 70 crops. Standard nitrogen fertilizer application levels for cereal crops changed from 94 kg/ha in 1960s, 99 kg/ha in 1970s, 110 kg/ha in 1980s to 90 kg/ha in 1990s. The K2O-fertilizer also changed from 67 kg/ha in 1960s, 76 kg/ha in 1970s, 92 kg/ha in 1980s, and only 44 kg/ha in 1990s. In rice paddy fields, the average contents of Cd, Cu, Pb, and Zn in surface soils (0-15 cm depth) were 0.11 mg kg(-1) (ranged from 0 to 1.01), 4.70 mg kg(-1) (0-41.59), 4.84 mg kg(-1) (0-66.44), and 4.47 mg kg(-1) (0-96.70), respectively. In the uplands, the average contents of Cd, Cu, Pb, Zn, and As in surface soils (0-15 cm depth) were 0.135 mg kg(-1) (ranged from 0 to 0.660), 2.77 mg kg(-1) (0.07-78.24), 3.47 mg kg(-1) (0-43.00), 10.70 mg kg(-1) (0.30-65.10), and 0.57 mg kg(-1) (0.21-2.90), respectively. In plastic film houses, the average contents of Cd, Cu, Pb, Zn, and As in surface soil were 0.12 mg kg(-1) (ranging from 0 to 1.28), 4.82 mg kg(-1) (0-46.50), 2.68 mg kg(-1) (0-46.50), 31.19 mg kg(-1) (0.19-252.0), and 0.36 mg kg(-1) (0-4.98), respectively. In orchard fields, the average contents of Cd, Cu, Pb, Zn, As, and Hg in surface soils (0-20 cm depth) were 0.11 mg kg(-1) (ranged from 0-0.49), 3.62 mg kg(-1) (0.03-45.30), 2.30 mg kg(-1) (0-27.80), 16.60 mg kg(-1) (0.33-105.50), 0.44 mg kg(-1) (0-4.14), and 0.05 mg kg(-1) (0.01-0.54), respectively. For polluted soils with over the warning content levels of heavy metals, fine red earth application, land reconsolidation and soil amelioration such as lime, phosphate, organic manure, and submerging were recommended. For the countermeasure areas, cultivation of non-edible crops such as garden trees, flowers, and fiber crops; land reformation; and heavy application of fine red earth (up to 30 cm) were strongly recommended. Land use techniques should be changed to be harmonious with the environment to increase yield and income. Soil function characteristics should be taken into account.     

Role of phosphate solubilizing bacteria on rock phosphate solubility and growth of aerobic rice

Use of phosphate-solubilizing bacteria (PSB) as inoculants has concurrently increased phosphorous uptake in plants and improved yields in several crop species. The ability of PSB to improve growth of aerobic rice (Oryza sativa L.) through enhanced phosphorus (P) uptake from Christmas island rock phosphate (RP) was studied in glasshouse experiments. Two isolated PSB strains; Bacillus spp. PSB9 and PSB16, were evaluated with RP treatments at 0, 30 and 60 kg ha(-1). Surface sterilized seeds of aerobic rice were planted in plastic pots containing 3 kg soil and the effect of treatments incorporated at planting were observed over 60 days of growth. The isolated PSB strains (PSB9 and PSB16) solubilized significantly high amounts of P (20.05-24.08 mg kg(-1)) compared to non-inoculated (19-23.10 mg kg(-1)) treatments. Significantly higher P solubilization (24.08 mg kg(-1)) and plant P uptake (5.31 mg plant(-1)) was observed with the PSB16 strain at the highest P level of 60 kg ha(-1). The higher amounts of soluble P in the soil solution increased P uptake in plants and resulted in higher plant biomass (21.48 g plant(-1)). PSB strains also increased plant height (80 cm) and improved root morphology in aerobic rice. The results showed that inoculation of aerobic rice with PSB improved phosphate solubilizing activity of incorporated RP.     

Effect of organic materials and rice cultivars on methane emission from rice field

A field experiment was conducted for two years on a sandy loam (Typic Ustochrept) soil of Punjab to study the effect of organic materials and rice cultivars on methane emission from rice fields. The methane flux varied between 0.04 and 0.93 mg m(-2) hr(-1) in bare soil and transplanting of rice crop doubled the methane flux (0.07 to 2.06 mg m(-2) hr(-1)). Among rice cultivars, significantly (p < 0.05) higher amount of methane was emitted from Pusa 44 compared to PR 118 and PR 111. Application of organic materials enhanced methane emission from rice fields and resulted in increased soil organic carbon content. The greatest seasonal methane flux was observed in wheat straw amended plots (229.6 kg ha(-1)) followed by farmyard manure (111.6 kg ha(-1)), green manure (85.4 kg ha(-1)) and the least from rice straw compost amended plots (36.9 kg ha(-1)) as compared to control (21.5 kg ha(-1)). The differential effect of organic materials in enhancing methane flux was related to total carbon or C:N ratio of the material. The results showed that incorporation of humified organic matter such as rice straw compost could minimize methane emission from rice fields with co-benefits of increased soil fertility and crop productivity.     

Four-decade responses of soil trace elements to an aggrading old-field forest: B, Mn, Zn, Cu, and Fe

In the ancient and acidic Ultisol soils of the Southern Piedmont, USA, we studied changes in trace element biogeochemistry over four decades, a period during which formerly cultivated cotton fields were planted with pine seedlings that grew into mature forest stands. In 16 permanent plots, we estimated 40-year accumulations of trace elements in forest biomass and O horizons (between 1957 and 1997), and changes in bioavailable soil fractions indexed by extractions of 0.05 mol/L HCl and 0.2 mol/L acid ammonium oxalate (AAO). Element accumulations in 40-year tree biomass plus O horizons totaled 0.9, 2.9, 4.8, 49.6, and 501.3 kg/ha for Cu, B, Zn, Mn, and Fe, respectively. In response to this forest development, samples of the upper 0.6-m of mineral soil archived in 1962 and 1997 followed one of three patterns. (1) Extractable B and Mn were significantly depleted, by -4.1 and -57.7 kg/ha with AAO, depletions comparable to accumulations in biomass plus O horizons, 2.9 and 49.6 kg/ha, respectively. Tree uptake of B and Mn from mineral soil greatly outpaced resupplies from atmospheric deposition, mineral weathering, and deep-root uptake. (2) Extractable Zn and Cu changed little during forest growth, indicating that nutrient resupplies kept pace with accumulations by the aggrading forest. (3) Oxalate-extractable Fe increased substantially during forest growth, by 275.8 kg/ha, about 10-fold more than accumulations in tree biomass (28.7 kg/ha). The large increases in AAO-extractable Fe in surficial 0.35-m mineral soils were accompanied by substantial accretions of Fe in the forest's O horizon, by 473 kg/ha, amounts that dwarfed inputs via litterfall and canopy throughfall, indicating that forest Fe cycling is qualitatively different from that of other macro- and micronutrients. Bioturbation of surficial forest soil layers cannot account for these fractions and transformations of Fe, and we hypothesize that the secondary forest's large inputs of organic additions over four decades has fundamentally altered soil Fe oxides, potentially altering the bioavailability and retention of macro- and micronutrients, contaminants, and organic matter itself. The wide range of responses among the ecosystem's trace elements illustrates the great dynamics of the soil system over time scales of decades.     

Case study on nitrogen and phosphorus emissions from paddy field in Taihu region

The agricultural non-point source pollution by nitrogen (N) and phosphorus (P) loss from typical paddy soil (whitish soil, Bai Tu in Chinese) in the Taihu Lake region was investigated through a case study. Results shown that the net load of nutrients from white soil is 34.1 kg ha(-1) for total nitrogen (TN), distributed as 19.4 kg ha(-1), in the rice season and 14.7 kg ha(-1) in the wheat season, and for total phosphorus (TP) 1.75 kg ha(-1), distributed as 1.16 kg ha(-1) in the rice season and 0.58 kg ha(-1) in the wheat season. The major chemical species of N loss is different in the two seasons. NH4-N is main the form in the rice season (53% of TN). NO3-N is the main form in wheat season (46% of TN). Particle-P is the main form in both seasons, (about 56% of TP). The nutrient loss varied with time of the year. The main loss of nutrients happened in the 10 days after planting, 64% of TN and 42% of TP loss, respectively. Rainfall and fertilizer application are the key factors which influence nitrogen and phosphorus loss from arable land, especially rainfall events shortly after fertilizer application. So it is very important to improve the field management of the nutrients and water during the early days of planting.     

氟虫双酰胺对蚯蚓的生化毒性与细胞毒性研究

双酰胺类杀虫剂已成为全世界第4大类最常用的杀虫剂,具有非常广阔的应用前景。然而,目前关于双酰胺类杀虫剂生态毒性评估方面的研究还比较少。为探究双酰胺类杀虫剂对非靶标生物的毒性作用,选取赤子爱胜蚓(Eisenia fetida)为受试生物,研究了典型双酰胺类杀虫剂氟虫双酰胺对非靶标动物蚯蚓的生化毒性和细胞毒性以及其在人工土和蚯蚓体内的浓度变化情况。结果表明,氟虫双酰胺在人工土壤中十分稳定,在整个暴露期间氟虫双酰胺的浓度变化不超过20%。氟虫双酰胺在蚯蚓体内的含量随染毒浓度的升高和暴露时间的推移而增加,呈明显的时间和剂量-效应关系;在染毒浓度为0.1和1.0 mg·kg-1的处理组中,氟虫双酰胺未对蚯蚓产生明显的氧化胁迫效应。在染毒浓度为5.0和10.0 mg·kg-1的处理组中,蚯蚓体内活性氧(ROS)含量显著高于其他处理组,过量的ROS诱导蚯蚓体内各种抗氧化酶活性发生异常变化,并在蚯蚓体内造成了脂质过氧化、蛋白质羰基化和DNA损伤。研究表明,当土壤中氟虫双酰胺的浓度为5.0和10.0 mg·kg-1时可能会对蚯蚓产生很高的风险。此外,彗星实验对氟虫双酰胺诱导的氧化胁迫较为敏感,可以作为敏感生物标志物对氟虫双酰胺造成的土壤污染进行预警。     

Effect of phosphogypsum amendment on soil physico-chemical properties, microbial load and enzyme activities

Phosphogypsum (PG) is produced as a solid waste from phosphatic fertilizer plants. The waste slurry is disposed off in settling ponds or in heaps. This solid waste is now increasingly being used as a calcium supplement in agriculture. This study reports the effectof PG amendmenton soil physico chemical properties, bacterial and fungal count and activities of soil enzymes such as invertase, cellulase and amylase over an incubation period of 28 days. The highest mean percent carbon loss (55.98%) was recorded in 15% PG amended soil followed by (55.28%) in 10% PG amended soil and the minimum (1.68%) in control soil. The highest number of bacterial colonies (47.4 CFU g(-1) soil), fungal count (17.8 CFU g(-1) soil), highest amylase activity (38.4 microg g(-1) soil hr(-1)) and cellulase activity (38.37 microg g(-1) soil hr(-1)) were recorded in 10% amended soil. Statistically significant difference (p<0.05) has been recorded in the activities of amylase and cellulase over the period of incubation irrespective of amendments. Considering the bacterial and fungal growth and the activities of the three soil enzymes in the control and amended sets, it appears that 10% PG amendment is optimal for microbial growth and soil enzyme activities.     

A study on the spatial distribution of nitrogen and phosphorus balance, and regional nitrogen flow through crop production

The spatial distribution patterns of the nitrogen and phosphorus input/intake amounts in crop production within two small basins are examined, based upon a cropping unit distribution map that is obtained from remote sensing data analysis. Firstly, we examine the availability and suitability of approaches to the spatial distribution analysis of cultivation patterns classified from material flow characteristics of crop production using seasonal remote-sensing data. Secondly, material flow units in crop production are grouped according to the cultivation patterns obtained from the remote-sensing data analysis. Consequently, the spatial patterns of the amounts of both nitrogen and phosphorus inputs/intakes through crop production on farmland are examined and their spatial distribution maps are prepared according to the material flow units. In addition, we developed a nitrogen flow and runoff model and the model is simulated based on the examination of the results of spatial distribution patterns of the material flow units. The annual nitrogen runoff from small catchments, where various crops are cultivated, varies from 2.7 kg ha(-1) year(-1) to 108 kg ha(-1) year(-1) and the annual balanced losses of nitrogen in small catchments varied from -30 kg ha(-1) year(-1) to 101 kg ha(-1) year(-1). Also, the monthly changes in soil nitrogen of each material flow unit is estimated at -55 kg ha(-1) as a maximum decrease and 114 kg ha(-1) as a maximum increase. These results indicate that the spatial distribution patterns of nutrient input and intake through agricultural activities should be considered when analyzing the material flows and nutritient movement in soil-water systems in rural areas for watershed environmental control and regional agricultural management.     

Glutathione S-transferase activity in rats exposed to methyl parathion

Methyl parathion is an organophosphate insecticide that has been used in agriculture and the domestic sector for several years. This pesticide and others, arriving through different processes, exert significant effects on water quality with serious consequences for environmental and human health. The main objective of this study was to investigate the changes of Glutathione S-transferase enzyme activity in methyl parathion exposed rat tissues. For this purpose, wistar rats (Rattus norvegicus) were injected intraperitoneally with 7 mg kg^?1 dose of methyl parathion, while corn oil was applied to control groups in the same way. The liver, kidneys, brain and small intestine were quickly removed after 0, 2, 4, 8, 16, 32, 64, and 72 hours of injection of methyl parathion and the glutathione S-transferase activity was determined in these tissues. As a result it was seen that glutathione S-transferase activity increases in all tissues in the group of male and female rats to which methyl parathion was given. The increase of glutathione S-transferase activity may be a result of methyl parathion's toxic effect because it is one of the most important enzymes of detoxification metabolism.     

Soil properties and root biomass responses to prescribed burning in young Corsican pine (Pinus nigra Arn.) stands

Fire is an important tool in the management of forest ecosystems. Although both prescribed and wildland fires are common in Turkey, few studies have addressed the influence of such disturbances on soil properties and root biomass dynamics. In this study, soil properties and root biomass responses to prescribed fire were investigated in 25-year-old corsican pine (Pinus nigra Arn.) stands in Kastamonu, Turkey. The stands were established by planting and were subjected to prescribed burning in July 2003. Soil respiration rates were determined every two months using soda-lime method over a two-year period. Fine (0-2 mm diameter) and small root (2-5 mm diameter) biomass were sampled approximately bimonthly using sequential coring method. Mean daily soil respiration ranged from 0.65 to 2.19 g Cm(-2) d(-1) among all sites. Soil respiration rates were significantly higher in burned sites than in controls. Soil respiration rates were correlated significantly with soil moisture and soil temperature. Fine root biomass was significantly lower in burned sites than in control sites. Mean fine root biomass values were 4940 kg ha(-1) for burned and 5450 kg ha(-1) for control sites. Soil pH was significantly higher in burned sites than in control sites in 15-35 cm soil depth. Soil organic matter content did not differ significantly between control and burned sites. Our results indicate that, depending on site conditions, fire could be used successfully as a tool in the management of forest stands in the study area.     

甲基对硫磷降解菌DLL-1的分离、鉴定及降解性研究

从长期施用甲基对硫磷的污染土壤中分离到一株能以甲基对硫磷为唯一碳源生长且能将其完全矿化的细菌 Ｄ Ｌ Ｌ－ １ ,经鉴定,为邻单胞菌（ Ｐｌｅｓｉｏｍｏｎａｓ ｓｐ ．） ．该菌株３ ｈ 内对５０ ｍｇ／ Ｌ甲基对硫磷的降解率为９３ ％ ,２４ｈ 内对５０ ｍｇ／ Ｌ甲基对硫磷的降解率为９５ ％ 以上．在葡萄糖铵盐培养基中, Ｄ Ｌ Ｌ１ 对甲基对硫磷的耐受浓度和降解速度均增大．降解曲线表明延滞期内,菌体依靠上一生长阶段分泌的酶类对甲基对硫磷进行降解,一旦菌体开始生长,则检测不到中间代谢产物对硝基苯酚的存在．生长情况和粗酶液试验均显示 Ｄ Ｌ１ 优良的降解性状     

Transport of the insecticides chlorpyrifos,chlorfenvinphos, carbofuran,carbosulfan, and furathiocarb from soil into the foliage of cauliflower and Brussels sprouts plants grown in the field

In several field assays made in different locations in 1988 and 1989, cauliflower and Brussels sprouts plants were treated some days after plantation by pouring onto soil around the stem of the plant one of the insecticides chlorpyrifos, chlorfenvinphos, carbofuran, carbosulfan, or furathiocarb, for protection against the root fly. During plant growth, each of the insecticides (and their soil metabolites) was transported from soil into the plant foliage, where it could give—during a certain period of time—a secondary plant protection against the foliage insects. The foliage concentrations of the non systemic chlorpyrifos and chlorfenvinphos were equal or greater than 1 mg/kg fresh weight during a period of about 44 days after soil treatment in Brussels sprouts crops, and 35 days in cauliflower crops. Comparison of 1988 and 1989 however showed that these periods of time changed according to the weather conditions, especially rainfall. These periods of time were greater when the insecticide soil concentrations were greater—and thus when the rates of insecticide soil metabolism were smaller— and when the rainfall were greater—water transporting the insecticides from soil to the foliage. Similar relationships were observed with the systemic insecticides carbofuran, carbosulfan and furathiocarb; the weights per plant of insecticide compounds transported from soil into the foliage however were greater with these systemic insecticides than they were with the non systemic chlorpyrifos and chlorfenvinphos. The extreme values observed for the periods of time of insecticide foliage concentrations equal or greater than 1 mg/kg fresh weight thus were: 1. in cauliflower crops: 21 to 36 days for chlorpyrifos, and 23 to 39 days for chlorpyrifos + oxon; 24 to 37 days for chlorfenvinphos; 20 to 48 days for carbofuran; 2. in Brussels sprouts crops: 43 to 49 days for chlorpyrifos; 47 to 53 days for chlorpyrifos + oxon; 41 to 45 days for chlorfenvinphos; between 2 to 3 months for carbofuran, carbofuran + carbosulfan, and carbofuran + furathiocarb in the fields treated respectively with either carbofuran, carbosulfan, or furathiocarb. Moreover, in the spring and summer cauliflower crops made on fields onto which continuous cauliflower crops—with their soil insecticide treatments—had been made since a greater number of years (greater soil “history”), the insecticide compounds soil and foliage concentrations generally were lower.     

Impact of phosphorous on biochemical changes in Hordeum vulgare L. in mixed cropping with chickpea

Multiple cropping (i.e. intercropping or mixed cropping) plays an important role in agriculture because of the effective utilization of resources, significantly enhancing crop productivity compared with that of monocultured crops. The study was planed to assess the effect of various concentrations (00, 30, 60, 90 kg ha(-1)) of phosphorous on the biochemical composition of grains of Hordeum vulgare L. (NDB-1050) in mixed cropping system with Chickpea. Phosphorous is an essential ingredient for plants to convert atmospheric N (N2) into an ammonium (NH4) as a useable form. The available nitrogen content was found more in the year 2006 (131 kg ha(-1)) than year 2005 (105 kg ha(-1)). The results of available nitrogen content were showed that the mixed cropping system enhances N fixation process because phosphorous also influences nodule development through its basic functions in plants as an energy source. Reducing, non reducing and total sugar content of H. vulgare L. were influenced by changes in the phosphorous doses. Maximum protein (13.43%) was obtained at 60 kg P2O5 ha(-1) during the year 2006. Lysine, tryptophan and methionine content were found maximum in year 2006, respectively. Total mineral content of grains of plant (0.99 g 100g(-1)) was found maximum by the application of 60 kg P2O5 ha(-1). It is possible that there was an increase in the soil N made available by the leguminous chickpea species, and this could be another reason why there was an increase in Hordeum vulgare L. shoot mass per plant with intercropping with chickpea.     

Degradation of benzo[a]pyrene in soil with arbuscular mycorrhizal alfalfa

Mycorrhizal and non-mycorrhizal alfalfa (Medicago sativa) was grown in pots containing soil artificially contaminated with various levels of benzo[a]pyrene (B[a]P) (0, 1, 10 and 100 mg kg(-1)). Soil and plants were sampled after 30, 40, 50, 60 and 90 days and compared with unlanted pots. The percentage of mycorrhizal root length colonized by Glomus caledoniun was not significantly affected by the addition of B[a]P up to 10 mg kg(-1) but was significantly lower at 100 mg kg(-1)B[a]P compared with low concentrations (p < 0.05). There was no difference in soil polyphenol oxidase and dehydrogenase activity among the controls and applications of 1 and 10 mg kg(-1) of B[a]P. However, enzyme activities were significantly higher at 100 mg kg(-1) B[a]P compared with the other three treatments, and there was no mycorrhizal effect. Over a period of 90 days the concentration of B[a]P in soil in which alfalfa was grown was significantly lower than in unplanted soil (p < 0.05). Degradation rates of B[a]P added at 1, 10 and 100 mg kg(-1) without G. caledonium were 76, 78 and 53%, and with mycorrhizal inoculation were 86, 87 and 57%. The degradation rate in unplanted soil was significantly lower than in planted soil, and was significantly higher in medium- and low-B[a]P treatments than in the high B[a]P concentration tested. There is a possibility of enhancement phytoremediation of PAHs in rhizosphere soil with arbuscular mycorrhizal fungi.     

Sulphur management in onion (Allium cepa) cultivation in hills of Himachal Pradesh

Field experiment were conducted at CSK HPKV Research Farm, Palampur during Rabi seasons of 2000-01 and 2001-02, to study the response of onion (Allium cepa var Patna red) at four sulphur levels (0, 15, 30 and 60 kg ha(-1)) applied through Gypsum and S95. The analysis was done to allocate the limited availability of sulphur for maximizing net profit over fertilizer cost. The results show that the dose of sulphur under its full availability is 43.02 kg ha(-1). But under its scarce availability the maximum benefit would occur when it is applied up to 32.11 kg ha(-1) followed by even distribution of fertilizer i.e. 20 kg ha(-1). The returns following sulphur application at these rates, would be Rs 69340, 73092 and 68700 ha(-1) respectively.