Open Access Original Research Article

Role of Soil Nitrogen for the Conifers of the Boreal Forest: A Critical Review

Carlo Lupi, Hubert Morin, Annie Deslauriers, Sergio Rossi, Daniel Houle

International Journal of Plant & Soil Science, Page 155-189
DOI: 10.9734/IJPSS/2013/4233

Nitrogen is considered the most important element in plant nutrition and growth. However its role and availability for boreal forest conifers is still debated. Boreal conifers have adapted strategies to cope with the reduced availability of N. ECM fungi, associated with boreal conifer roots, increase soil exploration and N nutrition, especially where organic N predominates. Conifers usually take up ammonium at levels comparable to simple organic N, which probably grows in importance as organic matter accumulates with stand age, while estimates of nitrate uptake are generally lower. Conifers, especially slow growing species, may rely on internal N cycling to sustain the development of new tissues in spring. N increases photosynthesis and leaf area and thus increases growth and wood formation, leading to wider radial rings mostly because of increased earlywood production. N-depositions and disturbances (e.g. fire and harvest) may alter the soil N-cycle and affect boreal forest growth. N depositions are considered responsible for the increase in boreal forest growth during the last century. Intensive harvest and high N-depositions may shift limitation from N to another element (e.g. P, K, and B). Climate change should affect the N cycle through complex mechanisms, including changes in the fire return interval, direct effects of warmer soils on N mineralization and stimulating plant growth modifying the balance between N stored in soils and in the living and dead (e.g. wood) biomass. Future research should try to improve our understanding of the possible outcomes of changes in disturbance regimes, N-depositions and climate, including the role of N fixation by mosses, canopy N uptake and the responses of conifers in relation to changes in microbial (symbiotic and not) communities.

Open Access Original Research Article

Performance of Okra (Abelmoschus esculentus L.) and Maize (Zea mays) under Okra/Maize Intercrop as Influenced by Nutrient Sources at Ibadan, Nigeria

Gerald O. Iremiren, Rotimi R. Ipinmoroti, Olufemi S. O. Akanbi

International Journal of Plant & Soil Science, Page 190-201
DOI: 10.9734/IJPSS/2013/4796

Farmers' practice of planting more than one crop under mixed cropping without fertilizer application has been a source of concern in Nigerian agriculture due to inherent low fertility status and fragile nature of the soils. This study was set up to assess the performance of okra (Abelmoschus esculentus L.) and maize (Zea mays) under okra/maize intercrop as influenced by nutrient sources at Ibadan, Nigeria Okra (Abelmoschus esculentus L.) and maize (Zea mays) were each sown as sole and in mixed crop at 1, 2 and 3 seeds hole-1. Fertilizers were used as organic {kola (Kola nitida) pod husks, KPH} applied at 5 and 10 t ha-1 and inorganic (NPK) applied at 80 and 160 kg N ha-1 and control The field experiment was conducted in randomized complete block design with three replicates at Ibadan, Nigeria on 30 April, 2010 for early cropping and 15 August, 2010 for late cropping season. Data obtained included okra plant height, girth, fruit yield and grain yield for maize. The land equivalent ratio (LER), aggressivity and monetary value (MV) were calculated. Okra plant height, girth, fruit and maize grain yield values were significantly higher in sole than in mixed cropping in both early and late cropping seasons. The fertilizers resulted in significantly higher okra performances compared to the control during both cropping seasons. The NPK fertilizer reduced okra yields in the late season compared to the early season, while it increased for KPH fertilizer. Maize grain yield in both seasons was in similar trend to that obtained for okra fruit yield. Planting okra and maize in mixture at 2 plants stand-1resulted to LER values that were generally greater than unity and resulted to 5.7-45-7% of land area saved, with low level of aggressivity and higher monetary value (MV) compared with sole maize and okra. The use of 2-plants stand-1 was optimum for better performance of okra and maize either planted sole or as okra/maize intercrop, while KPH @ 5 tons ha-1 and NPK @ 80 kg N ha-1 were optimal rates for better growth and yield of okra and maize both in monoculture and intercrops.

Open Access Original Research Article

Quantifying Medicago sativa Yield under Deficit Irrigation Technique in Sandy Soil

W. M. M. Omran

International Journal of Plant & Soil Science, Page 202-211
DOI: 10.9734/IJPSS/2013/4981

Deficit irrigation technique was introduced to find the best means to conserve irrigation water in arid lands. The most common model describing deficit irrigation is water yield response model. The main advantage of such model is that it can predict relative yield drop, which arises from relative water deficit, in order to maximize the economic return. The disadvantage of the model is that it uses evapotranspiration (ET), estimated by using meteorological data, which affects the applicability of the model when there is no weather station near the field. Furthermore, the sudden changes of weather parameters and the differences of the areas covered with green plant at different growth stages might also, affect the model applicability. Therefore, the research objectives were suggesting a modified version of FAO model, using soil moisture data instead of meteorological data to provide greater accuracy and applicability and validating the proposed model. Pot experiment was conducted to achieve these objectives. Four levels of soil available water were chosen to irrigate five cultivars of Medicago sativa (as one of the most important grazing crops) cultivated in two different soils (un-reclaimed). The results showed positive linear correlation between available soil water and crop yield at all the experimental treatments. Regression equations were developed to predict crop yield resulting from water deficit. The study indicated that the maximum yield is not necessarily the optimal one to maximize the profit in arid lands. The study recommended the modified model to predict yield drop and water saving and also, presented guidelines for water management of other similar plants grown in arid lands.

Open Access Original Research Article

Growth and Yield Performances of Fluted Pumpkin (Telfairia occidentalis Hook F.) under Organic and Inorganic Fertilizer on Ultisols of North Central Nigeria

E. Ndor, S. N. Dauda, M. N. Garba

International Journal of Plant & Soil Science, Page 212-221
DOI: 10.9734/IJPSS/2013/3863

The experiments were conducted during 2010 and 2011 rainy seasons at the research and teaching farm of the college of agriculture, Lafia, Nasarawa state, Nigeria. To determine the effect of urea fertilizer and poultry manure on the performances of fluted pumpkin (Telfairia occidentalis) in southern guinea savanna agroecological zone of north central Nigeria. The treatments consisted of three levels of urea fertilizer 0, 40 and 80 kg/ha and three levels of poultry manure: 0, 5 and 10t/ha factorially combined to form nine treatments which were laid in a Randomized Complete Block Design (RCBD) and replicated three times to form twenty seven plots. The result show that, application of urea and poultry manure rates did not significantly (p=0.05) affected vine length and number of leaves at 4 and 5weeks after germination in both cropping season. However, 6 weeks after germination application of urea and poultry manure produced a significant (p=0.05) effect on vine length and number of leaves in both season. 80kg/ha of urea produced the longest vine length of 74.80cm; 78.33cm in both years which are statistically comparable to 40kg/ha of urea but significantly higher than the control. 10t/ha of poultry manure generally recorded the best vine length (76.31cm and 79.23cm) in both years which is also comparable with application of 5t/ha of poultry manure; but significantly higher than the control(68.02cm and 68.57cm) in both years. Application of 80 kg/ha of urea fertilizer produced the highest number of leaves 27.46 in 2011cropping season, but was statistically the same with application of 40kg/ha of urea. 10t/ha of poultry manure also recorded the highest number of leaves 27.43 which is statistically the same with 5t/ha of poultry manure in both years. Urea fertilizer showed a significant (p=0.05) effect on the fresh biomass yield in 2010 cropping season. In 2011, urea fertilizer and poultry manure had a significant (p=0.05) response on fresh biomass yield of fluted pumpkin. Application of 80kg/ha of urea fertilizer produced the best biomass yield of 1134.52kg/ha, which is at par with application of 40kg/ha but higher than the control. Also, 10t/ha of poultry manure recorded a higher biomass yield of 1234.42kg/ha; which is also comparable with 5t/ha of poultry manure. Application of 40kg/ha of urea fertilizer and 5t/ha of poultry manure produced the best level of interaction. Therefore, this study recommend application of 40kg/ha of urea fertilizer and 5t/ha of poultry manure for environmentally friendly production of fluted pumpkin in North Central Nigeria.

Open Access Original Research Article

Coefficient and Path Analyses of the Impact of Root Galls Caused by Meloidogyne javanica on Some Growth and Yield Parameters of Tomato (Solanum lycopersicum)

S. I. Ogwulumba, K. I. Ugwuoke

International Journal of Plant & Soil Science, Page 222-229
DOI: 10.9734/IJPSS/2013/3510

Pot experiments were used to examine the impact of root galls caused by Meloidogyne javanica on some growth and yield parameters of tomato (Solanum lycopersicum) in Federal College of Agriculture Ishiagu, Ebonyi State, SE Nigeria in 2009 and 2010. The experiment was arranged in completely randomized design with four replications. Correlation and path coefficient analyses were used to determine the extent of the biological associations between number of galled roots with gall index, plant height, number of leaves, number of fruits and fresh fruit weight of three varieties (Roma, Roma VF and UC82B) of tomato. The results indicated strong positive correlations with gall indices and strong negative correlations with plant height, number of leaves, number of fruits and fresh fruit weight. The number of galled roots showed high positive direct effects on the gall indices and low positive effects on the fresh fruit weight. There were negative direct effects on the plant height and the number of leaves. The analyses showed that the negative effects on the growth parameters account for the reduction in the yield of the plants.

Open Access Original Research Article

Preliminary Diagnosis and Recommendation Integrated System (DRIS) Norms for Hevea brasiliensis Grown in the Humid Forest Zone of Cameroon

Jetro Nkengafac Njukeng, Eugene Ejolle Ehabe, George Elambo Nkeng, Ewald Schnug

International Journal of Plant & Soil Science, Page 230-243
DOI: 10.9734/IJPSS/2013/5107

The main source of natural rubber is the Hevea brasiliensis, an important crop to the Cameroonian economy. In order to improve yields in a sustainable manner, nutrient norms must be derived for proper nutrient and sustainable soil fertility management. The aim of this study was to derive Diagnosis and Recommendation Integrated System (DRIS) norms for Hevea brasiliensis grown under the ecological conditions of Cameroon. A survey of 130 Hevea brasiliensis fields was carried out to collect leaf samples and yield data. The leaves were analysed for N, P, K, Ca, Mg, S, Fe, Mn, Mo, Na and Zn. Using the yield data, the sampled population was divided into high- and low–yielding sub-populations. The DRIS norms were derived from a high-yielding sub-population (fields yielding >1, 486kg/ha) following standard procedures. Some of the DRIS norms obtained as ratios of nutrients presented significant differences between low- and high- yielding sub-populations. The DRIS norms were made up of ratios of macro nutrients, ratios of micro nutrients as well as ratios of macro and micro nutrients. Some of the obtained norms were different from literature reports that locally derived norms can be more accurate for nutrient diagnostic purposes. The DRIS indices were calculated and used for the assessment of the nutrient status of a low- yielding sub-population of Hevea. The results showed that most macro nutrients were deficient. The obtained nutrient norms will be used for nutrient assessment in Hevea plantations in Cameroon.

Open Access Original Research Article

Evaluation of Cultivated and Wild Plant Macroremains from a Predynastic Temple in Hierakonpolis - Upper Egypt

Mohamed A. Fadl, Ahmed G. Fahmy, Wael M. Omran

International Journal of Plant & Soil Science, Page 244-262
DOI: 10.9734/IJPSS/2013/4893

Hierakonpolis archaeological site was a Predynastic occupation (3800-3500 B.C.) where the early Egyptian civilization originated. The research aims to discover the cultivated crops in this remote time to recognize life activities of early Egyptians, reconstruct weeds assemblage grow within these crops, also wild plants give us a lot of information about climate and environment prevailed in this time. To reach this aim, soil samples were collected from Predynastic temple area. The samples were sieved and examined under the binocular objective using fine brush and needles and the plant remains were analyzed. Wood and charcoal of native trees were predominant. Cereal refuses, rhizomes, culm fragments, leaves, floral heads were mixed with mud to plaster floor and walls of the temple. Wood of native tall trees like Acacia niloticaTamarix aphyllaTamarix nilotica and Balanites aegyptiaca could have been used for building purposes inside the temple. Comparison and integration of our data with previous archaeobotanical informations from Hierakonpolis, Adaima and El Kab increase our knowledge about habitats and past vegetation of Upper Egypt during Predynastic period. Also agriculture practice and food habits of the old Egyptians were recognized. Triticum dicoccum and Hordeum vulgare were the most important crops. Remains of introduced plant species revealed the relations between inhabitants of Hierakonpolis and their neighbors in the east and south.