Organic Quantity Research Articles

Effects of different amounts of organic fertilizers on growth and production of tilapia in monoculture

The experiment was conducted to determine the effects of different amounts of organic fertilizers on growth and production of Tilapia (monosex GIFT tilapia) in monoculture system for a period of 120 days. The experiment was carried out in six earthen ponds, which were situated at the south-east corner of the Fisheries Faculty Building under the Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh. The experiment was designed with three treatments and each of them consisted of two replications. Fish population density was 120 fish per decimal for all the treatments. Ponds were treated with organic fertilizers (cow dung) at the rate of 2 kg, 4 kg and 6 kg per decimal were supplied fortnightly for treatment-I, treatment-II and treatment-III, respectively. The ranges of water temperature, transparency, dissolved oxygen, total alkalinity, free CO2, phosphate-phosphorus and nitrate-nitrogen found were 15.82 to 24.49 ºC, 17.00 to 32.00 cm, 7.00 to 10.30 mg L-1, pH 7.20 to 7.90, 140.00 to 192.00 mg L-1, 2.00 to 6.00 mg L-1, 1.40 to 1.95 mg L-1 and 3.30 to 3.73 mg L-1, respectively. All the physical and chemical parameters except temperature were within the productive range and more or less similar among all the ponds under three treatments. 18 genera of phytoplankton under five major groups and 9 genera of zooplankton under three major groups were identified in the experimental ponds. Average survival rate of fish under treatment-I, treatment-II, and treatment-III were 94.50%, 94.00% and 95.00%, respectively. The calculated net fish production under treatment-I was 3.554 ton ha-1 yr-1 and that under treatment-II was 3.648 ton ha-1 yr-1 and under treatment-III was 2.919 ton ha-1 yr-1. The net fish productions under treatment-II and treatment-III were 102.64% and 82.13% comparing with treatment on which was taken for 100%. According to cost-benefit analysis, the ratios of net profit under treatments I, II, and III were 1:0.81, 1:0.54, and 1:0.04. According to specific growth rate, treatment-II was the best and survival rate of treatment-III was the best, and according to cost-benefit analysis, treatment-I (ratio 1:0.81) was the best. So, organic fertilizer at the rate of 2 kg per decimal (treatment-I) was considered the best among three treatments in this experiment.
 Int. J. Agril. Res. Innov. & Tech. 8 (2): 24-31, December, 2018

Effects of physicochemical properties of different substrates on characters and yield of maize

A reasonable method was used to analyze the effects of different substrates on the characters and yield of maize, and to improve the quality and yield of maize. The effects of the maize characters and yield of national Fluvo-aquic soil fertility and fertilizer efficiency monitoring base were analyzed from 6 aspects: fertilization and combined application, fertilization and density coupling, controlled release fertilizer (CRF), fertilization level, fertilization depth and proportion, and the amount of organic manure (chicken manure). Data processing is done by using Excel2003 and SPSS17.0 software, and multiple comparisons are made by using Duncan’s new multiple range test method. The experiment of the influence factor of fertilization and combined application shows that the combination of NPK+ organic fertilizer (constant and high) can increase maize character ratio and NPK+ high-amount organic manure can increase maize yield. The experiment of the influence factor of fertilization and density coupling shows that the maize characters reached the optimum under the condition of high fertilizer. The yield of maize is highest when the density is 60000 plants /hm2 and the amount of fertilizer is 10.71kg, 3.57kg and 8.93kg per 667m2. The experiment of the influence factor of controlled release fertilizer shows that the characters of CRF V and CRF VI are the best. The control time of CRF III, CRF V, CRF VI, and CRF IV compound fertilizer is long, which can increase maize yield. The experiment of the influence factor of fertilizer level shows that the best character of maize is achieved by using the controlled release fertilizer of Agricultural University 450 kg/hm2 and two-topdressing 600 kg/hm2. In the process of corn production, the use of A-40 treatment (Volfertile controlled release fertilizer 600kg/hm2) and the one-time application of base fertilizer can increase the yield of maize. The experiment of the influence factor of fertilization depth and proportion show that the best combination is that seed fertilizer 20% urea, 40% diammonium phosphate and potassium sulfate were applied under the surface of 8cm and base fertilizer 40% urea, 60% diammonium phosphate and potassium sulfate were applied under the surface of 16cm. It can improve the character and yield of maize at the same time. The experiment of the influence factor of organic manure (chicken manure) shows that the amount of organic fertilizer (chicken manure) 26923kg per hectare with fertilizing 35kg per plot is the best amount of fertilizer, and the yield of maize increases. The proposed method can comprehensively and accurately analyze the effects of different substrates on the character and yield of maize, which can promote rational fertilization in maize and improve the quality and yield of maize steadily.

Growth and Micronutrients Contents of Smell Pepper (Capsicum chinense Jac.) Submitted to Organic Fertilizer

The results of research with smell pepper cultivation are still incomplete and preliminary, especially regarding organic fertilizing and nutritional status. The aims of study were to evaluate the effect of rates of organic fertilizer produced from family agriculture waste on growth and nutritional status of smell pepper. An experiment was conducted in a greenhouse at the Universidade Federal Rural da Amazônia, in Belém city, State of Pará, in period from January to April 2012. The experimental design was completely randomized, with five treatments and four replications, in which each experimental plot being made of a vase with a volume of 3.6 dm3 of soil and a smell pepper seedling. Five rates of organic fertilizer (0%, 15%, 30%, 45%, and 60%) were tested out of the total volume of substrate. The organic fertilizer were formed by mixing chicken manure (10%), duck manure (20%), cassava peel (15%), cassava leaf (15%), bean straw (15%), rice husk (15%), and corn cob (10%). The different amounts of organic fertilizer were mixed in volumetric proportions of substrate of Yellow Latosol, sandy texture, taken from the surface layer (0-20 cm). It was founded that at 103 days, the best results were achieved with a rate of 60% of the organic fertilizer. The content and accumulation of micronutrients in leaf tissue of smell pepper plants followed this descending order: Fe > B > Mn > Zn > Cu, and Fe > B > Mn > Zn > Cu, respectively. In fruits, the content, accumulation, and extraction of micronutrients followed this order: Fe > B > Mn > Zn > Cu.

Distribution of Phosphorus in Soil Profiles after Continuous Application of Different Fertilizers

This study clarifies the distribution and migration characteristics of phosphorus in the soil profile and discusses the phosphorus load of farmland after continuous application of different organic fertilizers. The distribution and migration characteristics of phosphorus in soil profiles were studied through a field experiment lasting four consecutive years. The results showed that total phosphorus and Olsen-P are mainly accumulated in the soil surface, and their contents decrease with the deepening of soil depth after the continuous application of different fertilizers. With a four-year application of higher levels of organic fertilizer, the total phosphorus was found to migrate into the 15-30 cm soil layer. Olsen-P was found to migrate into the 60-90 cm soil layer under higher levels of pig manure. The ratio of available phosphorus to total phosphorus in the soil surface increased, and there were significant differences after the application of different amounts of organic fertilizers. The amount of Olsen-P as a proportion of total phosphorus in the soil profile decreased as pig manure treatment > chicken manure treatment > sludge treatment > phosphate fertilizer treatment. After the application of chicken manure, pig manure, sludge, and phosphate fertilizer, the value of Olsen-P in the soil surface increased with an increase in phosphorus input and then remained stable. When applying the same phosphorus onto the soil, the contribution of different organic fertilizers to Olsen-P in the surface soil was quite different. The bioavailability and mobility of phosphorus from pig manure was significantly higher than that of chicken manure, sludge, and phosphate fertilizer.

Effect of mineral N fertilizer reduction and organic fertilizer substitution on soil biological properties and aggregate characteristics in drip-irrigated cotton field.

A four year field study was conducted to determine how soil biological properties and soil aggregate stability changed when organic fertilizer and biofertilizer were used to reduce chemical fertilizer application to a drip irrigated cotton field. The study consisted of six fertilization treatments: unfertilized (CK); chemical fertilizer (CF, 300 kg N·hm-2; 90 kg P2O5 · hm-2, 60 kg K2 O·hm-2); 80% CF plus 3000 kg·hm-2organic fertilizer (80%CF+OF); 60% CF plus 6000 kg·hm-2organic fertilizer (60%CF+OF); 80% CF plus 3000 kg·hm-2biofertilizer (80%CF+BF); and 60% CF plus 6000 kg·hm-2biofertilizer (60%CF+BF). The relationships among soil organic C, soil biological properties, and soil aggregate size distribution were determined. The results showed that organic fertilizer and biofertilizer both significantly increased soil enzyme activities. Compared with CF, the biofertilizer treatments increased urease activity by 55.6%-84.0%, alkaline phosphatise activity by 53.1%-74.0%, invertase activity by 15.1%-38.0%, β-glucosidase activity by 38.2%-68.0%, polyphenoloxidase activity by 29.6%-52.0%, and arylsulfatase activity by 35.4%-58.9%. Soil enzyme activity increased as the amount of organic fertilizer and biofertilizer increased (i.e., 60%CF+OF > 80%CF+OF, 60%CF+BF > 80%CF+BF). Soil basal respiration decreased significantly in the order BF > OF > CF > CK. Soil microbial biomass C and N were 22.3% and 43.5% greater, respectively, in 60%CF+BF than in CF. The microbial biomass C:N was significantly lower in 60%CF+BF than in CF. The organic fertilizer and the biofertilizer both improved soil aggregate structure. Soil mass in the >0.25 mm fraction was 7.1% greater in 80%CF+OF and 8.0% greater in (60%CF+OF) than in CF. The geometric mean diameter was 9.2% greater in 80%CF+BF than in 80%CF+OF. Redundancy analysis and cluster analysis both demonstrated that soil aggregate structure and biological activities increased when organic fertilizer and biofertilizer were used to reduce chemical fertilizer application. In conclusion, the organic fertilizer and the biofertilizer significantly increased SOC, soil enzyme activity, and soil microbial biomass C and N. The organic fertilizers also improved soil aggregation. Therefore, soil quality could be improved by using these fertilizers to reduce chemical fertilizer application, especially under drip-irrigation.

ANALISIS USAHATANI TEMBAKAU POLA KEMITRAAN DAN MANDIRI DI DESA LAMUK KECAMATAN TLOGOMULYO KABUPATEN TEMANGGUNG

One of the plantation sub-sector is now growing quite significantly is tobacco, where most farmers grow tobacco because this plant is considered to provide more added value when compared to other subsectors. Temanggung is known for quality tobacco than the tobacco of any area. To overcome the problem of capital and other issues, the majority of tobacco farmers in Temanggung working with the company’s domestic tobacco industry. Through this business partnership is expected to be fast so that the mutualistic symbiosis flaws and limitatation faced by tobacco farmers can be resolved. This study aims to : (1) knowing the production and the factors that influence the producton of tobacco and independent partnership (2) tp find out the income and factors that affect farm income on tobacco and independent partnership (3) to find out the allocative efficiency of input use on tobacco farming and independent partnership (4) knowing the risks of production and the risk of tobacco farm income.This study uses secondary data and primary by taking 60 farmers sample of 30 farmers and 30 farmers partnership patterns independently. To determine tha factors affecting farm production and income patterns of tobacco use and independent partnership Ordinary Least Square regression (OLS), to know the iffernce between the tobacco farm income and independent partnership used different test, to determine the allocative efficiency an production risk and income risk using coeffisien variation.Based on the result of the analysis indicate that the factors that influence the production is labor, the amount of organic fertilizer, the amount of inorganic fertilizrr, pesticides and dummy partnership, while the factors that affect revenue is the price of pesticide, land area, and dummy partnership. From the test resultas show the efficiency, not allocative efficient. Production risk and the risk of partnership income of farmers is higher than the patterm of independent farmers.

Evaluating Dairy Manure as Initial Fertility Driver for Mudflat Soil Amendment

The mudflats along the East Coast of China can be important alternative sources for arable lands if amended by large amount of organic fertilizers. Rich in organic matter and other nutrients, dairy manure has been considered as the economic choice for an initial fertility driver. Therefore, the goal of this study was to evaluate the impact of dairy manure amendment (DMA) as an initial fertility driver at application rates of 0, 30, 75, 150, and 300 t ha–1 on soil physicochemical properties, biomass and growth of ryegrass (Lolium perenne L.) grown in mudflat soil. The results showed that the DMA decreased soil bulk density in comparison to the unamended soil. The organic matter (OM) content in mudflat soil increased with increasing DMA rates. The salinity of mudflat soil decreased with increasing DMA rates, and the salinity at 30, 75, 150 and 300 t ha–1 DMA rates, corresponded to decreases of 26.1%, 35.8%, 37.8% and 45.4%, compared to 8.63 g kg–1 in the unamended soil. Electric conductivity (EC) of mudflat soil decreased with increasing DMA rate, while cation exchange capacity (CEC) increased duo to DMA. The contents of total N, total P, alkaline N, and available P in mudflat soil increased with increasing DMA rates. The increment of green herbage yield of ryegrass at 210 DAS at 30, 75, 150, and 300 t ha–1 DMA rates were 257.7%, 303.5%, 414.8%, and 516.6%, compared to the unamended soil (p < 0.05). Soil total Cu and Zn increased while total Mn, Ni, and Cr remained unchanged in response to DMA due to the high Cu and Zn content in the dairy manure. However, The DMA increased most of available metals except for Ni. In summary, land application of dairy manure as initial fertility driver could be an effective and safe way to amend mudflat soil, due to the rapid development of soil initial fertility, which enhanced green manure ryegrass (Lolium perenne L.) growth.

Comparison of Irrigation Qualities of Septic Tank Effluents Reclaimed Using Aerobic- versus Anaerobic-Based Treatment Systems

Conventional septic tanks remove partially suspended solids andorganics from wastewater, but they do not remove nutrients and pathogens. TheKuwait Institute for Scientific Research (KISR) studied a number of promisingsystems for the reclamation of effluents from conventional septic tanks. Thispaper compares the irrigation qualities of the final products of aerobic- versusanaerobic-based post-treatment systems. Reclamation of the effluents of a fullscaleconventional septic tank indicated that an anaerobic-based treatmentsystem resulted in lower salinity, fewer suspended solids, and smaller amountsof organics than an aerobic-based treatment system. However, the aerobicbasedtreatment system was found to be more efficient in the removal of totalnitrogen. Obtained results have also indicated that both treatment systems givealmost the same concentrations of boron and heavy metals. Therefore, it hasbeen concluded that reclamation of effluents of conventional septic tanksrequires both aerobic and anaerobic biological treatments

Different Responses of the Quality Parameters of Coriandrum sativum to Organic Substrate Mixtures and Fertilization

In order to standardize the quality of agricultural products, it is necessary to control the factors affecting plant development, such as plant nutrition. The best results in terms of homogeneity of the quality of vegetable crops were achieved using inert substrates and application of nutrients; however, production costs are high due to the cost of irrigation systems and substrate management and importation. This work aims to evaluate the effect of the local substrate mix and the amount of organic fertilizer on different quality parameters of coriander. To evaluate the quality of coriander, we considered different parameters such as size, biomass, antioxidant capacity and aroma (evaluated by volatile compounds detection with gas chromatography). The results show that the culture system differentially affects each parameter, and the compounds associated with the aroma of coriander and the diameter of plants are sensitive to the culture system, while the length of plants, number of leaves and antioxidant activity are not affected by the concentration of fertilizer. Moreover, organic farming conditions do not reduce quality parameters of the crops when using adequate fertilization. Additionally, local substrates would be practical substitutes for expensive importations.

NITROGEN UPTAKE OF SRI PADDY FIELD COMPARE TO CONVENTIONAL FIELD

The aim of this research is to compare nitrogen uptake in SRI field and conventional paddy field. Three SRI plots and three conventional plots were given same amount of organic fertilizer and three different biochar amount. In SRI field, S1 were plot with 5 ton/ha biochar application, S2 were plot with 10 ton/ha biochar application, and S3 were plot with 20 ton/ha biochar application. Similarly, in conventional paddy field, K1, K2, and K3 were plots with 5 ton/ha, 10 ton/ha, and 20 ton/ha biochar application. Mineral fertilizer were not used in this research. Result shows that, Nitrogen uptake in SRI paddy field (average of 262.9 mg/g Dry mass) were less than Conventional paddy field (average of 323.8 mg/g Dry mass). However, average of the grain weight of 1000 paddy grain shows that grain from SRI field is heavier (average of 20.7 g) than conventional paddy field (average of 19.0 g). Biochar application of 5 ton/ha, for both SRI and conventional fields shows higher result in most of plant parameters (plant height, amount of grain, total weight). SRI method usually shows the high production compare to conventional method. However, in this experiment there is almost no difference in SRI field (3.6 ton/ha) and conventional field (3.7 ton/ha). Plant observation shows that SRI paddy develop good rooting system than conventional paddy field that implies on more nutrient uptake. Soil were suspected to be the cause of low nitrogen uptake in SRI field.

Growth, Yield and Nutrient Uptake of Radish as Affected by Amount of Organic Fertilizer in a Volcanic Ash soil

Growth, Yield and Nutrient Uptake of Radish as Affected by Amount of Organic Fertilizer in a Volcanic Ash soil

Organic fertilizer effects on growth, crop yield, and soil microbial biomass indices in sole and intercropped peas and oats under organic farming conditions

In a field experiment, peas (Pisum sativum L.) and oats (Avena sativa L.) were grown as sole crops and intercrops, fertilized with horse manure and yard-waste compost derived from shrub and garden cuttings at 10tCha−1 each. The objectives were to compare the effects of these organic fertilizer and cropping system in organic farming on (a) yield of peas and oats, grown as the sole crop or intercropped, as well as N2 fixation and photosynthetic rates, (b) the yield of wheat as a succeeding crop, (c) microbial biomass indices in soil and roots, and (d) microbial activity estimated by the CO2 evolution rate in the field and the amount of organic fertilizers, recovered as particulate organic matter (POM). In general, organic fertilizer application improved nodule dry weight (DW), photosynthetic rates, N2 fixation, and N accumulation of peas as well as N concentration in oat grain. Averaged across fertilizer treatments, pea/oat intercropping significantly decreased nodule DW, N2 fixation and photosynthetic rate of peas by 14, 17, and 12%, respectively, and significantly increased the photosynthetic rate of oats by 20%. However, the land equivalent ratio (LER) of intercropped peas and oats exceeded 1.0, indicating a yield advantage over sole cropping. Soil microbial biomass was positively correlated with pea dry matter yields both in sole and intercropped systems. Organic fertilizers increased the contents of microbial biomass C, N, P, and fungal ergosterol in soil and CO2 production, whereas the cropping system had no effects on these microbial indices. According to the organic fertilizer recovered as POM, 70% (manure) and 64% (compost) of added C were decomposed, but only 39% (manure) and 13% (compost) could be attributed to CO2–C during a 101-day period. This indicated that horse manure was more readily available to soil microorganisms than compost, leading to increased grain yields of the succeeding winter wheat.

Sulfur fractions in particle-size separates as influenced by long-term application of mineral and organic fertilizers

A field experiment established in 1962 was chosen to investigate the effect of long-term application of farmyard manure (FYM), compost (COM) and sewage sludge (SS), respectively, in two increments as compared to mineral fertilizer on inorganic and organic S fractions in particle-size separates (&amp;lt; 0.002 mm, 0.002&amp;ndash;0.02 mm, 0.02&amp;ndash;2 mm). Independent of the particle-size the application of the high amounts of COM and SS resulted in the highest total S contents. It is evident that the particle-size fractions &amp;lt; 0.002 mm contained the majority of total soil sulfur (S). The content of plant available S (water-soluble and adsorbed SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2&amp;ndash;&lt;/sup&gt;) decreased with increasing particle-size, while the influence of the kind and amount of organic fertilizers was negligible. As compared to C-bonded S sulfate esters were the dominant organic S fraction in size separates. The content of both organic S fractions was highest in the particle-size fraction &amp;lt; 0.002 mm and lowest in the particle-size fraction 0.02&amp;ndash;2 mm. The influence of the application of organic fertilizers was less pronounced. Only high application rates of COM and SS, respectively, resulted in the highest contents of both organic S fractions in the particle-size fractions 0.002&amp;ndash;0.02 mm and 0.02&amp;ndash;2 mm. &amp;nbsp; &amp;nbsp;

CHEMICAL AND PHYSICO-CHEMICAL CHARACTERIZATION, AND ANTIOXIDANT ACTIVITY OF ITALIAN TOMATOES (LYCOPERSICON ESCULENTUM MILL.) UNDER ORGANIC CROP MANAGEMENT

The purpose of this study was to evaluate the chemical and physico-chemical characteristics as well as to measure the antioxidant activity of two Italian tomato hybrids (‘San Vito’ and ‘HEM 031’), growing under organic production in Brazil. The hybrid cultivars are from Brazil and can be used fresh or processed. The amounts of organic compost applied were: 6, 12, 24, 40 t/ha, equivalent to 100, 200, 400, 800 kg/ha of N. The following was evaluated: the total soluble solids, total titratable acidity, pH, ascorbic acid, β-carotene and lycopene, mineral content (Na, Mg, P, K, Ca, Mn, Fe, Cu, Zn, Al) and antioxidant activity by TRAP, FRAP and TEAC assays. Results were analyzed by ANOVA and LSD tests, at 5% significant levels. Differences between both hybrids were observed only for total soluble solids, ascorbic acid and pH, with higher values for ‘San Vito’. The amount of organic fertilizer applied affected the hybrids’ total titratable activity. The lycopene and β-carotene contents were influenced by the interaction hybrid×fertilization levels. The lowest level of fertilization (100 kg/ha N equivalent) produced higher levels of lycopene and β-carotene only in ‘HEM 031’ hybrid, with no differences in ‘San Vito’. For mineral content, only K, Fe, Ca and P showed statistical differences. The Ca concentration increased with the level of fertilization. Increases in P concentration were observed in ‘HEM 031’ hybrid fertilized with 200 and 800 kg/ha of N, while in ‘San Vito’ hybrid, only the lowest level of fertilization decreased P concentration, comparing to the other fertilization levels. The specific hybrid, the level of fertilization and the assay applied, affected the antioxidant activity results. The hybrid ‘HEM 031’ showed higher values of K and Fe compared to ‘San Vito’.

Effects of Organic Manure on Nitrate Distribution in Greenhouse Soil over Three Continuous Crop Cultivations

An experiment was conducted on a vegetable planting base in Damintun Town, Xinmin City, Liaoning Province to study the influence of different organic manure rate on nitrate distribution in vertical profile in a greenhouse soil over three continuous crop cultivations of cucumbers, beans and lettuces. The soil was treated with organic manure at five treatments. The results showed that the distribution characteristic was closely related with organic manure rate in the process of plant growth. After harvest of the cucumber and lettuce soil nitrate content of all layers was higher than before planting and the accumulation of nitrate was increased with the application rate of organic manure. When applied into the low amount of organic fertilizer (M1 and M2), no significant phenomenon of nitrate accumulation and leaching occurred. High amount of organic manure rate (M4) increased significantly (P&lt;0.05), especially in 0~40cm soil layer. In the lower layer (60~120cm) of soil different degrees of nitrate leaching took place. The vertical distribution of nitrate before planting and harvest of beans showed that catch crops can effectively reduce the accumulation of nitrate in soil.

Organic Farming and Soil Carbon Sequestration: What Do We Really Know About the Benefits?

Organic farming is believed to improve soil fertility by enhancing soil organic matter (SOM) contents. An important co-benefit would be the sequestration of carbon from atmospheric CO2. Such a positive effect has been suggested based on data from field experiments though many studies were not designed to address the issue of carbon sequestration. The aim of our study was to examine published data in order to identify possible flaws such as missing a proper baseline, carbon mass measurements, or lack of a clear distinction between conventional and organic farming practices, thereby attributing effects of specific practices to organic farming, which are not uniquely organic. A total of 68 data sets were analyzed from 32 peer-reviewed publications aiming to compare conventional with organic farming. The analysis revealed that after conversion, soil C content (SOC) in organic systems increased annually by 2.2% on average, whereas in conventional systems SOC did not change significantly. The majority of publications reported SOC concentrations rather than amounts thus neglecting possible changes in soil bulk density. 34 out of 68 data sets missed a true control with well-defined starting conditions. In 37 out of 50 cases, the amount of organic fertilizer in the organic system exceeded that applied in the compared conventional system, and in half of the cases crop rotations differed between systems. In the few studies where crop rotation and organic fertilization were comparable in both systems no consistent difference in SOC was found. From this data analysis, we conclude that the claim for beneficial effects of organic farming on SOC is premature and that reported advantages of organic farming for SOC are largely determined by higher and often disproportionate application of organic fertilizer compared to conventional farming.

Effects of organic management on water-extractable organic matter and C mineralization in European arable soils

In this study we tested the hypothesis that water-extractable organic carbon (WEOC) content and its properties can be used to distinguish conventionally (CONV) from organically (ORG) managed arable soils as responsible for C mineralization. We sampled soils at three different European sites located in Mediterranean (Italy) and continental (Switzerland) regions under conventional and organic management. The Mediterranean sites are here called CVI and LSI and the continental one DOK. The main difference between the two management systems (ORG and CONV) at all sites was the amount of organic fertilizer yearly added into the soil: in the ORG systems 2.2–2.5 Mg C year −1 were added as organic fertilizer, while in the CONV systems only mineral fertilizers were used. Moreover, the crop rotation was different between the two management systems at first two sites (7 years-crop vs. 4 years-crop rotation), while at DOK site a 7 years-crop rotation was adopted in both managements. In these soils we analyzed C mineralization rate expressed as percentage of mineralized C in a 90-day incubation with respect to soil total organic C (qM), the content of water-extractable organic carbon (WEOC), its initial composition by fluorescence spectroscopy (humification index – HIX) and its biodegradability (ΔWEOC). The Mediterranean basic soil accumulated more organic C showing a more complex WEOC than continental acid soil. Moreover, among management practices the crop rotation seemed to be one of the most important factor affecting WEOC properties and C mineralization rate (qM). In particular the highest qM and WEOC content were observed in both systems with 7 years-crop rotation including pasture, such as alfalfa or grass clover, according to the order ORG(DOK) = CONV(DOK) > ORG(LSI) > ORG(CVI). With respect to the effect of the management systems on C mineralization rate and WEOC properties, significant differences of WEOC content were observed between ORG and CONV soils at all sites (5.7 vs. 7.7; 14.5 vs. 17.9; 6.8 vs. 13.5 at CVI, DOK and LSI, respectively), whereas qM and HIX were significantly different only at the Mediterranean sites (qM: 4.4 vs. 5.8 and 6.6 vs. 8.2; HIX: 9.4 vs. 13.7 and 3.4 vs. 13.6 at CVI and LSI, respectively). Therefore, we can conclude that WEOC content is not a generally applicable parameter to distinguish conventionally from organically managed soils as responsible for C mineralization. Specific cropping systems, soil properties and climate conditions should be considered as important factors affecting mineralization process and WEOC properties.

Interactive effects of organic fertilizer, CaSO4 and amino acid Ca on Fuji apple in Burozem soil in China

A two-year trial was conducted to test the interactive effects of special-for-apple organic fertilizer, CaSO4, and amino acid Ca on Fuji/Balenghaitang (Malus robusta Rehd.) rootstock in Burozem soil in China. Total Ca, exchangeable Ca, and fruit Ca were significantly improved by the soil application of CaSO4 with the highest exchangeable Ca and fruit Ca observed in Fuji apple trees treated at the rate of 3.5 kg CaSO4 per tree. 3.5 kg CaSO4 was divided into two applications, with first application in the first month after full bloom, and the second in the second month after full bloom in summer, progressively to improve fruit Ca concentration. Dividing CaSO4 into two applications in combination with organic fertilizer or amino acid Ca spray, proved to be more effective on improving the fruit Ca concentration, with the highest level of 179.17 mg/kg FW in Fuji apple trees treated with 2 kg CaSO4 applied and amino acid Ca sprayed in the first month after full bloom, 1.5 kg CaSO4 applied in summer, organic fertilizer applied in winter. Organic fertilizer applied in winter alone remarkably improved the fruit Ca concentration, as well as storage Ca in roots and stems, and the best effect was observed in Fuji apple trees which were supplemented organic fertilizer (10 kg) in winter and CaSO4 (1 kg) in the first month after full bloom per tree. The effect on Ca increment became less pronounced when the amount of organic fertilizer reached 15 kg or CaSO4 was more than 3.5 kg per tree. There was a positive correlation between the Ca/Mg ratio in soil and fruit, exchangeable Ca, and fruit Ca concentration, while a negative correlation was observed between the N/Ca ratio in fruit, available P, available K in soil, and fruit Ca concentration. Both N/Ca ratio and Ca/Mg ratio in fruit were affected by different fertilization regime, and bitter pit incidence at the end of storage kept acceptable only if N/Ca < 17 and Ca/Mg ≥ 7 at harvest. The commercial fertilization regime turned out to be organic fertilizer in combination with CaSO4 applied in soil in winter, amino acid Ca sprayed in the first month after full bloom, and CaSO4 applied in soil in summer.

Nitrogen in interstitial waters in the Sahel; Natural Baseline, Pollutant or Resource?

Nitrate in the unsaturated zone between the soil surface and the water table was studied in agroforestry Parklands in north western Senegal by examination of samples obtained by hand auger. Depending on location, water tables existed at depths between 10 and 35m below ground. Previous studies of groundwater in this region had found that large concentrations of nitrate were unconnected with anthropogenic activity. The objective of this study was to determine whether nitrogen fixing vegetation had a role in groundwater nitrate accumulation and whether roots of trees were located deeply enough to access the nitrate. Accordingly, sample profiles were augered close to stems of nitrogen fixing trees, non-nitrogen fixing trees and also in adjacent areas that were unaffected by tree presence. These adjacent areas were typically open pasture or cultivated fields. Tree fine roots were quantified in the samples and examined for the presence of mycorrhizas. Similarly, sand/soil samples were examined and tested for the presence of nitrogen fixing rhizobia that were capable of forming functional nodules on appropriate host plants. Concentrations of nitrate were greatest in soils beneath nitrogen fixing trees and nitrate was more plentiful in profiles augered beneath nitrogen fixing crops than it was elsewhere suggesting that N-fixation was the source of the nitrate. The concentrrations of nitrate that were found in the unsaturated zone were greatly in excess of the WHO recommended limit for nitrate in drinking water. High NO3-N/Cl ratios confirm insitu production of nitrate, and indicate that this is a natural baseline occurrence related to N-fixation. The nitrate is moving down the profile and impacts the groundwater unless it can be intercepted by plant roots. NO3-N amounts in solution in the soil profile varied between 75 and 1000kg ha−1 beneath trees and between 120 and 400kg ha−1 in areas outwith tree crowns. Although these quantities of N occupy the lower end of the range of N values obtained in north American deserts, they comprise a considerable dryland resource where amounts of organic fertilizer are limited and where cost prohibits the use of commercial fertilizers. Roots of both nitrogen fixing and non-nitrogen fixing trees were deep enough to access the nitrate but the small amounts of available water at intermediate depths suggest that large scale uptake of nitrate will only be possible in the wetter zones located close to the water table. Shallow roots tended to be more heavily colonized by mycorrhizas than deeper roots but mycorrhizas were recovered from roots located 22m below ground. Tree roots and rhizobia had similar patterns of distribution. They were commonest close to the soil surface, less frequent at intermediate depths and tended to increase in frequency close to the water table.

Factors affecting methane emissions from rice fields

Methane emissions from rice fields are affected by a number of environmental and agricultural factors. We have analyzed our 7‐year data set on methane emissions from rice fields in Tu Zu, China, to delineate the relationships between emissions and a number of variables that were measured at the same time. Our work was done in fields that were managed under prevailing agricultural practices of the region. Consequently, only the effect of factors that vary from year to year or during the growing season can be calculated. In our study we measured the effects of environmental variables (soil temperature, wind speed, sky cover) and agricultural factors (planting density, water level, rice cultivars, organic fertilizer amounts, yield). Of these variables, soil temperature had the most significant effect on methane emissions resulting in Q10 values of about 2 (1.5–3). The effect of sky cover, and even water levels, was to change the soil temperature, which in turn affected the methane flux. Wind tended to increase emissions, possibly by agitation of the soil. Of the agricultural variables, planting density had the most significant but complex effect on methane emissions. We studied emissions from up to 4 times the normal planting density under otherwise similar agricultural conditions in the same fields. For a four fold increase in planting density the seasonal average emissions increased by about a factor of 2. Rice cultivars had a small but detectable effect. The amount of organic fertilizer and the yields did not affect methane emissions in our fields. The lack of an effect from the fertilizers is attributed to a saturation phenomenon whereby methane emissions do not respond to continual increases in organic material after some sufficiently high level.