Influence of Long Term Fertilization with Different Mineral Fertilizers and Farmyard Manure on Some Soil Chemical Properties and Crop Yields *1

A long term fertilization experiment was carried out in an experimental field in Lyczyn near Warsaw, Poland. Application ofmineral fertilizers, especially N fertilizers with and without farmyard manure accelerated the acidification process of the soil. Application of 1.6 t CaO ha -1 every four years was essential to maintenance of the soil pH KCl at 5.5～6.6 and base saturation degree above 60%. Application of 50 t farmyard manure ha -1 every 4 years, which contained 46 kg P and 240 kg K, was sufficient to maintain both the K and P fertility of the soil. Besides, it was beneficial to alleviating soil acidification. As a result of long term unbalanced fertilization, yield responses to N, P and K fertilizers increased significantly with time. The efficiency of N from farmyard manure was found to be comparable to that of N fertilizer during 1988～1991.

On-farm Evaluation of Effect of Organic and Mineral Fertilizers on Biomass and Yield of Millet/Cowpea Intercrop in the Sahel, West Africa

To determine the best combinations of organic and mineral fertilizer applications under resource-limited conditions in the Sahel, West Africa, on-farm experiments for two years in the Fakara region of western Niger is conducted. Ten treatments were tested; six of them received one of three organic fertilizers （none, millet husks, or manure）, with or without mineral fertilizer; two grew millet/（dual-purpose） cowpea intercrops with mineral fertilizer in 1：1 or 4：4 row arrangement; one grew a millet/（spreading） cowpea intercrop with manure; and one grew a millet/hibiscus intercrop with millet husks. Manure increased total biomass by 127%- 147% （P 〈 0.001 ） and millet yield by 130%- 184% （P 〈 0.01 ）. Mineral fertilizer increased total biomass by 27% （P 〈 0.01 ） and millet yield by 24% （P 〈 0.05） in 2008. The N balance was greatest and positive in the manure treatment （P 〈 0.001）, followed by millet husks. Mineral fertilizer on the intercropped dual-purpose cowpea increased the agronomic N use efficiency of millet by 329%-483% （P 〈 0.01） compared with manure. The use of small quantities of mineral fertilizer on the intercropped dual-purpose cowpea, therefore, is a best combination for limited N-resources-farmers. Single manure, millet husks plus mineral fertilizer, or year-alternative-application are also recommendable depends on farmers accessibility to the resources.

Effects of Various Doses of Mineral Fertilizers(NPKS and Urea) on Yield and Economic Profitability of New Varieties of Zea mays L. in Faranah,Guinea

In Faranah Province （Guinea）, the ratio of supply and demand of corn is approximately 1 ： 2. The production is low and the deficit is covered by maize importation. This study was initiated in order to improve corn production by evaluating the effects of increasing doses of mineral fertilizers on the yield and economic profitability of corn. The experiment was conducted on a farm in Kamedankoude in a split plot with three replicates. Treatments included two varieties of maize （Perta and Kilissi113） and five doses of chemical fertilizers （D0=unfertilized control, Dl=300 kg NPKS＋200 kg urea. hm^2; D2=400 kg NPKS＋800 kg urea· hm^2; D3= 200 kg NPKS＋400 kg urea· hm^2 and D4=500 kg NPKS＋600 kg urea. hrn2）. The results showed that all the agronomic parameters increased with increasing dose of fertilizers, except for the number of ears per plant. The two varieties of corn tested produced similar yields. However, the profitability of mineral fertilizers decreased with increased doses and with value/cost ratio of 3. We recommended a mineral fertilizer dose of 300 kg NPKS ＋ 200 kg urea. The high prices of mineral fertilizers were often barriers to intensive maize cultivation, especially for low-income farmers. This study was a contribution to rational fertilization and adapted the socio-economic conditions of the region, with the background knowledge that most farmers in the regions earned low incomes.

Residual Effect of Long Term Application of Organic and Mineral Fertilizers on Selected Chemical Properties of a Savanna Alfisol

The residual effect of organic and mineral fertilizers on selected chemical properties of an Alfisol in the long term soil fertility trial established in 1950 at Samaru, Nigerian savanna was assessed. The trial was left fallow for fourteen years due to lack of funds. Topsoil was collected from plots that received three levels of cow dung （D）, nitrogen （N） and phosphorus （P） in all possible combinations. The soils were analyzed for selected chemical properties. Except for significant effect of applied P on available P, sole application of cow dung, N or P had no significant effect on all the measured soil properties. The interaction of D and P significantly affected the mean values of exchangeable Ca, Mg, K and ECEC in the range of 1.12-1.96, 0.62-1.11, 0.37-0.64 and 2.82-4.11 cmol/kg respectively. The most important results were the ability of the plot that received neither D nor P to significantly increase these parameters than the plots that received only one of the treatments. The results show that the fallow period has changed the effects of application of organic and mineral fertilizers on the soil chemical properties under continuous cultivation by modifying them towards those of a native savanna Alfisol.

Enhanced Growth and Yield Performance of Cassava Peel Compost and Mineral Fertilizer on Corchorus olitorius L.

Application of inorganic fertilizers improves crop yields but costs and adverse health effects often discourage their applications. This study therefore aims at evaluating the combined effects of cassava peel compost with poultry manure and mineral fertilizer on growth and yields of Corchorus olitorius. Pots （factorial laid out in a randomized complete block design） and field （split-plot with fertilizer being the main effect and the varieties the sub plot effect） experiments were carried out during rainy season at Ibadan, Nigeria. Treatments consisted of 0, 5, l0 and 20 t/ha composts prepared from cassava peel and poultry manure in ratio 3：1 and mineral fertilizer （NPK 15：15：15） at the rate of 250 kg/ha, using two varieties of C. olitorius. Five and six weeks after planting （WAP）, plants were assessed for growth and yields in pot and field experiments respectively, and also in residual studies. Application of compost significantly improved growth （heights） （36.50-41.56 cm）, while morphological and dry weight values increased with increase in compost. Marketable yield increase of 13.2%, 22.3%, 32.1% and 29.3% were recorded using 5, 10, 20 t/ha compost and NPK fertilizer respectively in the field. Corresponding increase when ratooned were 40.0%, 42.9%, 57.1% and 52.0%, respectively. Application of compost at the rate of 20 t/ha performed better in the main and residual effect experiments compared to NPK fertilizer and other compost rates. Application of cassavas peels compost at the rate of 20 t/ha proved to be adequate for optimum growth and yield performance of C. olitorius.

The influence of potassium to mineral fertilizers on the maize health

Field experiments （2009-2011） were conducted at the Department of Agronomy at Poznar~ University of Life Sciences on the fields of the Research Institute in Swadzim. We evaluated the health of maize plants of two types, depending on the variations in mineral fertilization. The conducted research recorded the occurrence of pests such as oscinella frit （Oscinella frit L.） and the European corn borer （Pyrausta nubilalis Hbn.）. Diseases recorded during the research included two patho- genes： Fusarium （Fusarium ssp.） and corn smut （Ustilago maydis Corda）. It was shown that the meteorological conditions during the maize vegetation had a significant influence on the occurrence of pests. Adding potassium to mineral fertilizers increased the maize resistance to Fusarium. Cultivation of ＂stay-green＂ cultivar shall be considered as an element of in- tegrated maize protection. The occurrence of oscineUa flit was correlated with the occurrence of Fusarium as well as the occurrence of the European corn borer for both examined cultivars.

Effect of Biofertilizers on the Agromorphological Parameters of Three Okra Cultivars in Southern Côte d’Ivoire

Okra (Abelmoschus esculentus L.) is an herbaceous plant of the Malvaceae family. In Côte d’Ivoire, okra production is estimated to be over 193,000 tons. This low production is largely due to poor soils and hardly covers the needs of the population. To remedy this, growers systematically use mineral fertilizers. However, these fertilizers pollute the environment. To find an alternative to chemical fertilization and increase production, the effect of biofertilizers (Spaawet, Retone, Super Gro) compared with NPK mineral fertilizer was evaluated on Divo, Teriman, and Djonan F1 cultivars. The trial was set up in a factorial block design with three replications. Plant height, number of functional leaves, and crown diameter were assessed at 60 days after sowing (DAS). The time to 50% flowering, production time, and fruit yield were calculated. The results showed that the biofertilizer Retone induced the highest heights and number of functional leaves, with averages of 61.89 cm and 29.88 leaves, respectively. The diameter at the crown (17.77 mm) was highest with the NPK mineral fertilizer, and the shortest 50% flowering time, with an average of 47.61 days, was also obtained with the biofertilizer Retone. The NPK mineral fertilizer produced the longest production time, with an average of 35.25 days. The highest yields were obtained using Retone (11.07 t/ha) and NPK (9.52 t/ha) fertilizers. The “Divo*Retone” interaction produced the highest yield with an average of 12.19 t/ha. The biofertilizer Retone could therefore be used as an alternative fertilizer to chemical fertilization in okra crops, given its effect on the parameters assessed.

The Position of Mineral Nitrogen Fertilizer in Efficient Use of Nitrogen and Land:A Review

Our attitude towards mineral nitrogen (N) fertilizers is ambivalent. N fertilizers have on one hand increased our supply of food, feed and other bio-based raw materials tremendously and also improved the use efficiency of land and labor, but have on the other hand a negative impact on the quality of the environment and contributed to the depletion of fossil fuel reserves. This awareness has resulted in strong pleas to spend much more attention to the recycling of N containing downstream “wastes”. It is, however, naive to assume that even perfect recycling suffices to offer the same number of people the same diet without inputs of “new” N, as inevitable losses of N make compensations indispensable. “New” N can be derived from either biological N fixation (“legumes”) or from industrially fixed N (“fertilizer”). The existing literature provides no evidence that the use of N fertilizers is per se unsustainable, as these fertilizers can also be made from renewable forms of energy. Besides, soil health and human health appear sensitive for the dosage but not for the form of N. It is yet imperative to reduce the input of “new” N as much as possible, so as to minimize adverse environmental effects. Measures to this end are a more precise assessment of crop N requirements, a better timing and positioning of N inputs, and any measure supporting the acceptance of “wastes” by farmers. The present paper elaborates the above aspects.

Mineral Coated Fertilizer Effect on Nitrogen-Use Efficiency and Yield of Wheat

A field experiment with winter wheat （Triticum aestivurn L.） was conducted on a silt loam calcaric endorusti-ustic Cambosols derived from the Yellow River alluvial deposits in Henan, China, from 2001 to 2002 to evaluate N recovery and agronomic performance of different mineral coated fertilizers （MiCFs） compared to normal urea used in wheat cropping systems under field conditions. Five treatments, including CK （check, no N fertilizer）, urea and three different MiCFs at an equivalent N application rate were established in a randomized complete block design. N release from MiCFs in soil was more synchronous with the N requirement of wheat throughout the growth stages than that from urea, with grain yield of the MiCF treatments significantly higher （P 〈 0.05） than that of the treatment urea. Correspondingly, the N recovery rate was greater for all MiCFs compared to urea, increasing from 32.8% up to 50.1%. Due to its high recovery and low cost, use of the mineral coated N fertilizers was recommended instead of the polymer coated N fertilizers.

Effects of Continuous Mineral and Organic Fertilizer Inputs and Ploughing on Groundnut Yield and Soil Fertility in a Groundnut-Sorghum Rotation in Central Burkina Faso

Two field experiments were conducted at Saria in the centre of Burkina Faso in order to assess the effect of chemical and organic fertilizers on yields and soil fertility on two different soils. Groundnut haulm yield, pod yield, number of pods, % 2-seeded pods, % pod rot, seed yield and 100 seeds weight as well as sorghum dry shoot and grain yields were measured. Most of the different variables were affected by continuous cropping without fertilizer application on the two soils, in particular on the coarse one. The effect of nutrient deficiencies was observed. The mineral fertilizers maintained yields, but their supply was not able to replenish the nutrient uptake by plants. The effect of compost on crop production was initially minimal, but improved during years seven and height. Tillage had also a slightly positive effect on yield, which varied with soil type. In the control plot, the content of organic matter decreased in five years and did not increase with the application of fertilizers. In contrast, addition of fertilizers increased total N and Bray-I P. Nitrogen, P, K and Ca balances were negative in almost all treatments without mineral fertilizers. Results showed that fertilizers used were inadequate for maintaining soil fertility and yields in long run. However, extra production did not provide significant profits.

Efficiency of Bio-Fertilizing as One of the Natural Alternatives to Improve the Growth of Khaya senegalensis and Swietenia mahagoni Trees and for Sustainability

A field experiment was carried out at Ismailia Research Station, Ismailia Governorate from 2020-2022 to improve the growth of Khaya senegalensis and Swietenia mahagoni by using a combination of mineral fertilizer (NPK) and biological fertilizer (Azotobacter chroococcum, Bacillus megatherium, and Bacillus circulant) as recommended dose under new sandy soils conditions. Split plot designed with four treatments (Control, (50% Mineral fertilizer (M.) + 50% Biological fertilizer (Bio.)), 100% M. and 100% Bio.) of each species. Vegetative growth, leaf area, tree biomass, stored carbon, basal area, tree volume, and in the soil both of microbial account and mineral content were determined. The experimental results showed no significant differences between studied species among the most studied parameters except for Khaya senegalensis which gave the highest significant difference in root biomass and below-stored carbon than Swietenia mahagoni. Evidently, the highest significant growth parameters were 100% mineral fertilizer followed by (50% M. + 50% Bio.) as compared with control. No significant difference between 100% M. and (50% M. + 50% Bio.) of shoot dry biomass (15.19 and 12.02 kg, respectively) and above-stored carbon (0.28 and 0.22 Mt, respectively). Microbial account and mineral content in soil were improved after cultivation of tree species compared to before planting and control, especially with 50% mineral fertilizer and 50% bio-fertilizer treatment. In conclusion, a treatment containing 50% mineral fertilizer and 50% bio-fertilizer has led to the ideal Khaya senegalensis and Swietenia mahagoni growth in sandy soil for cheaper and sustainable.

Soil CO_2 and N_2O Emissions in Maize Growing Season Under Different Fertilizer Regimes in an Upland Red Soil Region of South China

Upland red soils have been identified as major CO2 and N2O sources induced by human activities such as fertilization. To monitor characteristics of soil surface CO2 and N2O fluxes in cropland ecosystems after continuous fertilizer applications over decades and to separate the respective contributions of root and heterotrophic respiration to the total soil CO2 and N2O fluxes, the measurements of soil surface CO2 and N2O fluxes throughout the maize growing season in 2009 were carried out based on a fertilization experiment （from 1990） through of the maize （Zea mays L.） growing season in red soil in southern China. Five fertilization treatments were chosen from the experiment for study： zero-fertilizer application （CK）, nitrogen-phosphorus- potassium （NPK） fertilizer application only, pig manure （M）, NPK plus pig manure （NPKM） and NPK with straw （NPKS）. Six chambers were installed in each plot. Three of them are in the inter-row soil （NR） and the others are in the soil within the row （R）. Each fertilizer treatment received the same amount of N （300 kg ha-1 yr-1）. Results showed that cumulative soil CO2 fluxes in NR or R were both following the order： NPKS〉M, NPKM〉NPK〉CK. The contributions of root respiration to soil CO2 fluxes was 40, 44, 50, 47 and 35% in CK, NPK, NPKM, M and NPKS treatments, respectively, with the mean value of 43%. Cumulative soil N2O fluxes in NR or R were both following the order： NPKS, NPKM〉M〉NPK〉CK, and soil N2O fluxes in R were 18, 20 and 30% higher than that in NR in NPKM, M and NPKS treatments, respectively, but with no difference between NR and R in NPK treatment. Furthermore, combine with soil temperature at -5 cm depth and soil moisWxe （0-20 cm） together could explain 55-70% and 42-59% of soil CO2 and N2O emissions with root interference and 62- 78% and 44-63% of that without root interference, respectively. In addition, soil CO2 and N2O flUXeS per unit yield in NPKM （0.55 and 0.10 kg C t^-1） and M （0.65 and 0.13 g N t^-1） treatments were lower than those in other treatments. Therefore, manure application could be a preferred fertilization strategy in red soils in South China.

Integrating phosphorus management and cropping technology for sustainable maize production

Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective approach for achieving high maize yields.However,the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.In this study,meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.A significantly higher yield was obtained at higher plant densities than at lower plant densities.The application of single superphosphate,triple super-phosphate,and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.Further,the P resource use efficiency throughout the P supply chain increased by 39%,whereas the P-related environmental footprint decreased by 33%.Thus,simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production,indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.These findings offer strategic,synergistic options for achieving sustainable agricultural development.

Photosynthetic Pigments Affected by Fertilizer Source in Four Brassica Vegetables

Effect of fertilizer source （mineral fertilizer or organic manure） on photosynthetic pigments leaves content of four brassica vegetables （Pak choi, Kohlrabi, Cauliflower and Cabbage） was tested. Among treatments, cauliflower fertilized with chicken manure had the highest content of chlorophyll a and b （10.08 and 9.37 μm·g^-1）, while, pak choi had the lowest values （2.00 and 2.44 μm·g^-1） in non-fertilized plants. These differences in chlorophyll a and b content may have a great impact on photosynthetic rate and activity. Total carotenoids and total xanthophylls （lutein, zeaxanthin, antheraxanthin and violaxanthin） were the highest in cauliflower while the lowest was in pakchoi, β-carotene, on the other hand, was the highest percentage of total carotenoids （65.7%） in pak choi while Kohlrabi had the lowest percent （57.4%）. This high percentage offl-carotene of total carotenoids may compensate for lower content of chlorophylls and assist for efficient light harvesting process. Lutein showed to be the major components of xanthophyll pigments brassica vegetables and ranged from 0.462μm·g^-1 in cabbage to 0.626μm·g^-1 in kohlrabi but not differed significantly which may refer to genetically controlled. However, lutein, antheraxanthin and zeaxanthin content were increased significantly by the application of chicken manure regardless ofbrassica vegetable type. Violaxanthin was only detected in pak choi and not affected by fertilizer source. It can be concluding from the increasing contents of total xanthophylls pigments that may increase photosynthetic efficiency through non-photochemical quenching process.

Influence of Mineral Fertilization on the Capacity of Nodulation of Three Species of Legumes(Groundnut,Cowpea and Soybean)

Groundnut (Arachis hypogaea), cowpea (Vigna unguiculata) and soybean (Vigna radiata) are the main food legumes grown in Cote d’Ivoire and the localities of Haut-Sassandra. These legumes are highly valued for their nutritional, agronomic and economic value. Groundnut, cowpea and soybean are the main food legumes grown in Cote d’Ivoire and in the localities of Haut-Sassandra. On the other hand, Ivorian soils are characterized by a tendency towards acidification and a decrease in the content of nutrients such as phosphorus and nitrogen which have a direct impact on the products. To restore soil fertility, farmers use mineral fertilization. However, this fertilization has an influence on the nodulation of these legumes. The study took place at Jean Lorougnon University. We adopted a completely random experimental block device. The parameters measured included the number of nodules, the length and weight of the plant, the length and weight of the root system. Our results showed that mineral fertilization reduced the nodulation capacity of legumes. However, a small dose of phosphorus ( g) would be required for early growing legumes.

Growth and nutrient accumulation of Brazil nut trees(Bertholletia excelsa) in agroforestry at different fertilizer levels

The Brazil nut tree（Bertholletia excelsa） is a frequent component of agroforestry systems in the Amazon because of its adaptation to nutrient-poor upland soils and multiple uses.We investigated the aboveground biomass production（kg dry weight）,nutrient uptake and requirements（N,P,Ca,Mg,K） of Brazil nut trees of different sizes grown under agroforestry conditions and fertilized at different levels.Eight of 70 experimental trees with different size were harvested and stem,branches and leaves were separated.Nutrient contents were determined for three trees of varying size.Average tree growth was fast,but variability was high,suggesting considerable potential for the improvement of this economically important species.The trees responded to increased levels of fertilizer and lime with significantly increased foliar nutrient contents and growth,probably because of the improved availability of Mg and Ca for which the species seems to have a relatively high demand.In contrast to Brazil nut trees grown in forest or dense plantations,the agroforestry trees invested a substantial part of their biomass and nutrients in large branches and developed spreading crowns.To improve stem form,reduce competition with associated crops for light and recycle nutrients,regular pruning of lower branches or planting arrangements that favor self-pruning are recommended.These measures would also increase the recycling of Ca and Mg,large quantities of which are contained in the branches.

Impact of Organic Soil Amendments on the Physical Characteristics and Yield Components of Potato （Solanum tuberosurn L.） in the Highlands of Cameroon

A field experiment was conducted in the Western Highlands of Cameroon to study the effects of Calliandra calothyrsus, sterilized compost, non-sterilized compost and mineral fertilizers （NPK 11：11：22） on physical characteristics, yield components and late blight disease severity of potato （Solanum tuberosum）. A two factorial treatment combination made up of fertilization schemes and sanitary measures were laid out in a randomized complete block design （RCBD） with four replicates and 10 treatments. Data collected were subjected to a multivariate ANOVA and means separated with the Dunnett t-test with Calliandra calothyrsus considered as the main treatment. Mineral fertilizers and Calliandra calothyrsus significantly augmented stem diameter, plant height and plant vigor, total and marketable yields, despite the fact that late blight severity was high in the two treatments. The correlation matrix showed that total yield had significant and positive correlation with stem diameter （r = 0.74）, plant height （r = 0.61）, plant vigor （r = 0.61） and marketable yield （r = 0.99） and negative correlation （r = -37） with late blight severity. The increase observed is attributed to the nutrient contents of the treatments applied. Leafy prunings of C. calothyrsus increase soil organic matter which probably improves moisture retention and biological activity. The highest late blight severity recorded between the 45 and 60 coincides with active development of plant canopy which influences disease severity and create a canopy microclimate conducive to disease development. This study suggests that Calliandra calothyrsus has the potential of improving potato production provided appropriate fungicide is used.

Effects of Sulfur and Manganese Micronutrients on the Yield of Soybean Varieties

In this article, it is given about lengthening of praxis period, stem and leaf growth, leaf surface, number of stems and weight than the control variant soybean varieties, and the yield and grain quality of soybean varieties are significantly higher when the three types of sulfur and manganese on background of mineral fertilizers are applied in suspension in the condition of meadow-swamp soil. In the soybean varieties, mineral fertilizers were used in the variant with an additional yield of around 5 - 12 c/ha compared to the control. According to the norms of the manganese element, around 7 - 20 c/ha;when using sulfur, the yield in soybean varieties is around 8.0 - 18.0 c/ha. On the background of mineral fertilizers, grain quality has changed due to micronutrients. Protein content in the “Orzu” variety increased by 3.1% - 8.4% when manganese and sulfur elements were used;in the “Nafis” variety, the protein content was found to increase by 6.1% - 8.5%.

Recent advances in the chemistry of nitrogen,phosphorus and potassium as fertilizers in soil:A review

The advent of civilization has made humans dependent on plants for food and medicine,leading to the intensification of agricultural production.The intense cultivation of crops has resulted in the depletion of available nutrients from soil,thereby demanding the application of excess nutrients to soil to improve yield.Thus,mineral fertilizer discovery and application have,in many ways,contributed greatly to meeting global food demands.However,aside from the positive effects of mineral fertilizers,their excessive application to soil produces large amounts of pollutants that affect environmental sustainability.This necessitates the study of the major mineral fertilizer elements(nitrogen(N),phosphorus(P),and potassium(K)),the forms in which they are applied to soil,and their chemistry/reactions in soil.Here,we reviewed the forms of different N,P,and K mineral fertilizers to provide current knowledge on their constituents,the chemistry of N,P,and K in soil to understand the reactions they undertake in soil,the efficient methods of fertilizer application for environmental sustainability,the effects of mineral fertilizer loss to the environment,and improved fertilization technologies for environmental sustainability.Nanofertilizers are a promising technology for sustainable agricultural production and are discussed in detail in this review.

Response of Soil Microbial Properties to Long-Term Application of Organic and Inorganic Amendments in a Tropical Soil (Saria, Burkina Faso)

Soil microbial biomass carbon (MBC), β-glucosidase, acid phosphatase and fluorescein diacetate (FDA) activities and bacterial community structure were assessed in a long-term (26 years) experiment, at physiological stages of sorghum growth, comparing different management methods for organic (manure, straw residues) and inorganic (urea) amendments at the INERA field station in Saria (Burkina Faso). Annual application of manure led to the highest soil microbial biomass and enzyme activities. Investigations indicated that only microbial biomass and β-glucosidase activities were affected during the cropping season. Phosphatase and FDA enzyme activities did not depend on the crop development stages. The application of N fertilizer modified phosphatase and FDA enzyme activities, the activities being higher in soils amended with N fertilizer. The bacterial community structure was analyzed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) targeting the eubacterial 16S rRNA gene. Cluster analysis of PCR-DGGE patterns showed two major clusters, the first containing the mineral fertilization and straw treatments and the second, the straw + urea, manure and manure + urea treatments. Sorghum grain yields were the highest for manure treatments. In this long-term experiment, applying straw did not produce a better grain yield than that obtained in the un-amended plot.