Greater Nutrient Accumulation Research Articles

The influence of the stubble biodestroyer and the main tillage method on the nutrient regime of the soil

Annually, soil fertility indicators decrease in Ukraine. Therefore, to ensure a deficit-free soil balance, it is necessary to attract additional reserves of organic raw materials, in particular, post-harvest residues of agricultural crops, and to use biological preparations for their destructuring. To date, the effect of stubble biodestructors on the processes of mineralization of post-harvest plant residues has not yet been fully studied, especially under different methods of main tillage, therefore the purpose of our study was to determine the influence of the destructor Ecostern Classic and the method of main tillage on its nutritional regime in the conditions of southern Ukraine. Research methods: field, laboratory. Research has established that the amount of nitrates, mobile phosphorus and exchangeable potassium that remained on average over the years of research in the soil of the experimental site after harvesting winter wheat was 6.3, respectively; 47.5 and 208.8 mg/kg of soil, and after harvesting winter barley – 5.9; 42.8 and 202.4 mg/kg of soil. After partial mineralization of plant residues of winter crops, in three months, the content of nutrients in the soil increased, especially when treated with the Ecostern Classic biodestroyer. It was determined that the use of plowing contributed to the acceleration of the mineralization of plant residues of winter wheat and the greater accumulation of nutrients in the soil. Thus, during the treatment of post-harvest remains of winter wheat with a biodestructor using plowing, 11.3 mg/kg of soil nitrates, 53.9 mg/ kg of soil of mobile phosphorus and 261.8 mg/kg of soil of exchangeable potassium were determined. For the processing of post-harvest remains of winter barley, the indicators were slightly lower – 10.5, respectively; 51.5 and 251.0 mg/ kg of soil. The practical value of the research lies in the improvement of the processes associated with increasing the fertility of the soils of southern Ukraine due to the much more rational use of post-harvest remains of winter wheat and barley

Bean nutrition and development in the function of reduced phosphorus doses and inoculation with arbuscular mycorrhizal fungus

It is widely accepted that mycorrhizal fungi increase phosphate fertilization efficiency. The objective of this study was to evaluate the effects of reduced phosphorus applications and inoculation with arbuscular mycorrhizal fungi (AMF) on the nutrition and initial growth of the carioca-type common bean (Phaseolus vulgaris L). The study was conducted at the Faculty of Engineering of Ilha Solteira, in the city of Ilha Solteira/SP, Brazil, where there was temperature and humidity monitoring as well as irrigation control. The experimental design was randomized blocks with a 5 × 2 factorial scheme and four replications. The treatments consisted of a combination of five doses of P2O5 (0%, 25%, 50%, 75%, and 100% of the recommended dose for beans) applied during sowing, with or without inoculation with AMF - Rhizophagus intraradices - at 200 g ha−1. The root volume, root dry matter, dry mass of the aerial part, and the concentration and accumulation of macro- and micronutrients in the aerial part were evaluated. Inoculation with AMF enhanced the root system, growth of the aerial part, and absorption of most nutrients, resulting in greater nutrient accumulation and increased phosphorus absorption. The combined inoculation and phosphate treatments increased the concentration and accumulation of nutrients in common beans.

Organic substrates and slow-realease fertilizing on nutrient accumulation and absorption efficiency of custard apple seedlings

There is a lack of agronomic research on the production of custard apple seedlings, especially regarding the ideal substrate and nutritional requirement of the plants. In order to evaluate the accumulation of nutrients in shoots and roots, leaf chlorophyll index and absorption efficiency index (AEI) in custard apple seedlings grown in different substrates and under doses of slow-release fertilizer, an experiment was set in randomized blocks in split-plot scheme with four replicates and eleven plants per plot. The custard apple seedling production method was by sowing. Plots were represented by substrates (fresh sugarcane bagasse; enriched sugarcane bagasse; coconut powder, and commercial organic substrate), whereas subplots were represented by Osmocote Plus® fertilizer doses (0; 3; 6; 9; 12 and 15 kg m-3). The final evaluation was performed at 105 days after sowing. The effect of the slow-release fertilizer on the formation of custard apple seedlings was influenced by the substrate. There was greater accumulation of nutrients as the availability of nutrients increases, as well as increase in nutrient AEI. Custard apple seedlings were found to be more efficient to absorb N > Mg > K > Ca > P > Fe > Mn > Zn. As substrate, coconut powder associated with the 9 kg m-3 slow-release fertilizer dose is recommended to produce custard apple seedlings.

Content and distribution of micronutrients in calendula (Calendula officinalis) grown in Valle del Cauca, Colombia

Calendula productivity depends on the nutritional demands of the crop. Knowledge of the nutritional requirements of calendula at its different phenological stages will allow the producer to improve fertilization programs. The objective of this research was to evaluate the content and distribution of essential micronutrients and beneficial elements in different organs and stages of development of calendula under field conditions. An experiment was set up in the municipality of Yumbo, in the Department of Valle del Cauca in Colombia, using a completely randomized design with five treatments related to the stage of development of the plants (2, 3, 5, 6 and 7 months after transplanting). Each treatment had three replicates. Leaves, stems, flowers and seeds were collected every month after transplanting to analyze the concentrations of Mn, Fe, Zn, Cu, B, and Na. The concentration of nutrients differed significantly between organs and stages of development. Calendula accumulated nutrients in descending order (from highest to lowest) as follows: Na>Fe>Mn>B>Zn>Cu. The highest concentrations of Na, Mn, Zn, B and Cu were found in the leaves and of Fe in the flowers. Among the phenological stages, the highest values of Na were recorded in the second and sixth months, B and Fe in the fifth month, Cu and Zn in the third month, and Mn in the third and fifth months. Thus, the stages and organs on the plant with the greatest nutrient accumulation were identified.

The production and composition of colostrum from ewes supplemented with niacin (vitamin B3)

Context Twin-bearing ewes may be unable to produce enough colostrum following birth to support the survival of two lambs. This causes the newborn lambs to be at risk of death due to starvation, mismothering, cold exposure and infection. Niacin has previously been demonstrated in cattle to increase immunoglobulin concentrations in colostrum, possibly due to niacin increasing blood flow, allowing the greater accumulation of nutrients and immunoglobulins in colostrum. High producing animals, such as the late gestation twin-bearing ewe, may not be able to produce enough niacin to meet their production requirements. Aims This experiment evaluated whether supplementation of niacin (vitamin B3) to late gestation twin-bearing ewes would increase colostrum production and composition (concentration of fat, lactose, protein and immunoglobulin G), and postnatal lamb growth. Methods A total of 24 artificially inseminated Merino ewes were weighed, body condition scored, aged and randomly allocated to a treatment – control treatment or with 5 g/day niacin supplemented for 2 weeks before lambing until 2–8 days post-lambing. Key results Colostrum production and immunoglobulin G concentration were similar between treatments (P > 0.05). Ewes supplemented with niacin produced significantly higher (P = 0.039) colostral protein at 12.54% compared with the control group ewes at 11.78%. Early lamb growth rates were unaffected (P > 0.05) by treatment. Conclusions Supplementation of ewes with 5 g/day niacin is not recommended to increase the production of colostrum and immunoglobulin G or to increase lamb growth rates following birth. Implications Further research into niacin supplementation, supplementation time and supplementation amount for production effects in late gestation ewes is warranted.

Inclusion of Babassu Decomposed Stem Substrates on the Pattern of the Vegetative Growth of Passion Fruit Seedlings

ABSTRACTThe objective of this study was to evaluate the biological rhythm of the vegetative growth and nutrient content of the yellow passion fruit seedlings produced in substrates with different levels of based on the decomposed stem and babassu (DBS): S1 – 20%, S2 – 40%, S3 – 60%, S4 – 80%, S5 – 100% DBS and S6: commercial. Were investigated the plant height (PH), stem diameter (SD), emergency speed index (ESI), germination (%G), leaves number (NL), root length (RL), root volume (RV), dry mass of the shoot (SDM), dry mass of the root system (DMRS), Dickson quality index (DQI) periodically for 60 days. The accumulated nutrient (N, P, K, Ca, Mg and B) contents were determined after this period. The data were submitted to ANOVA, significant means were compared by the Tukey test (P < .01). ANOVA results showed a significant effect (P < .01) for using DBS in 80% (S4 and S5) on RV, DQI, and DMRS in relation to the commercial one. In addition, there was greater accumulation (P < .01) of N, P, K and B in contents S4 and S5. Therefore, the use of the babassu decomposing stem as a substrate positively influences the vegetative growth rate of yellow passion fruit seedlings, especially due to its nutritional aspect, promoting a greater accumulation of nutrients, mainly boron. Mixing with the soil in the ratio 80/20, respectively, promotes the best biometric and nutritional responses, with the best quality conditions for seedling formation.

Potential of Species of Green Coverage in Entisol

The intensive use of the soil, associated with the application of chemical fertilizers, contribute to degradation processes that affect soil quality and crop production. The use of techniques that contribute to soil conservation and reduction of external inputsis important for the success of the agriculture, and hedging is an alternative. The objective of this study was to evaluate the phytomass production nutrient accumulation and contents, as well as rate of decomposition of different species used as cover plants. The experimental design was randomized blocks, with nine treatments distributed in three blocks. The treatments were: Canavalia ensiformes (L.) DC., Crotalaria spectabilis Roth, Crotalaria ochroleuca G. Don., Crotalaria juncea L., Dolichos lablab L., Stizolobium niveum (Roxb.) Kuntze, Stizolobium aterrimum Piper &amp;amp; Tracy, Neonotonia wightii (Wight &amp;amp; Arn.) J.A. Lackey and Pennisetum glaucum (L.) R.Br. The most recommended species as cover plants are C. ochroleuca and C. spectabilis for they produce more dry matter on the tops, 5.89 and 4.04 kg ha-1, in addition to greater accumulation of nutrients. C. ochroleuca and C. spectabilis had higher accumulation of N, P, K, Mg and S, and soil coverage with those species can be a good source of green manure. The recommended species for the highest coverage rate are: N. wightii; S. niveum and S. aterrimum. The recommended species for the lowest rate of decomposition are: S. aterrimum; S. niveum; P. glaucum and C. ochroleuca (0.245; 0.260; 0.264 and 0.276% month-1).

Millet irrigation with treated wastewater: Gas exchange response and nutrient accumulation

ABSTRACT Wastewater can be considered an excellent nutritional and water source for cultivated plants. However, the presence of high concentrations of salts and toxic compounds can negatively affect crops. The effect of irrigation with different concentrations of treated wastewater on the accumulation of nutrients and gas exchange aspects of millet (Pennisetum glaucum (L.) R. Br.) grown in clay soil and sandy loam soil was analyzed. This study was conducted in a greenhouse (16°40’57,50” S; 43°50’26,07” O; 650 m) in a 5 x 2 factorial design, consisting of five levels of concentration of treated wastewater (0, 25, 50, 75, and 100%), combined with two types of soil (clay and sandy loam). The experiment was designed in randomized blocks with four replicates. The increase in treated wastewater concentration in irrigation water applied to clay soil and sandy loam soil favored the increase of net photosynthesis, transpiration rate, stomatal conductance, leaf chlorophyll content and accumulation of macro- and micronutrients in millet plants. Millet plants grown in clay soil showed an average increase of 23% in gas exchange capacity and 71% in accumulation of macro- and micronutrients, when compared with treatments in sandy loam soil. Therefore, treated wastewater contributes to the increase in gas exchange capacity and greater accumulation of nutrients in millet plants, which represents an alternative for reduced demand for fresh water and use of chemical fertilizers.

Nutrient accumulation in Eucalyptus bark at different population densities

ABSTRACT The objective of this study was to quantify the accumulation of nutrients in the bark of four eucalyptus clones at 12 years-of-age, planted at different population densities, and the values were extrapolated to kg of nutrients per hectare. The experiment used randomized blocks in a 4 × 3 factorial design and three replications, with four Eucalyptus clones (2486, I182, I144, and GG100) planted at three population densities (416, 833, and 1111 trees ha-1). The rigorous cubage of three trees per plot was performed by collecting discs of bark at the following heights: diameter at breast height (1.30 m), 0, 25, 50, 75, and 100% of the commercial height of the stem. The bark discs of each tree were grouped and used to determine N, P, K, Ca, Mg, and S content, in addition to the basic density. The volume and dry mass of bark per tree was estimated and the accumulation of nutrients per tree ha-1 was estimated sequentially, for each population density. Analysis of variance and Tukey’s post-hoc tests verified that Ca showed the greatest accumulation in the bark, followed by N, K, S, Mg, and P. The increase in population density contributed to higher bark production and greater nutrient accumulation per hectare. However, this increase was not evident when comparing densities of 833 and 1111 trees ha-1.

Contribution of corn intercropped with Brachiaria species to nutrient cycling1

ABSTRACT The corn biomass and nutrient dynamics may be altered when it is intercropped with Brachiaria (syn. Urochloa spp.). The present study aimed to investigate the dynamics of biomass, nitrogen (N), phosphorus (P) and potassium (K) for farming systems that produce corn intercropped with Brachiaria species. Field experiments were performed during the season and off-season, in a split-plot design. The main plots were composed of Brachiaria species (B. brizantha,B. ruziziensis and B. Convert) intercropped with corn, in addition to corn monocropping. The subplots consisted of three forage sampling periods, ranging from 0 to 60 days after the corn harvest. The intercropping arrangements did not affect the corn grain yield, nutrient accumulation and partitioning, relatively to the corn monocropping. After the grain harvest, B. brizantha achieved the greater biomass accumulation rate in both the season (69 kg ha-1 day-1) and off-season (17 kg ha-1 day-1). The nutrient accumulation ranged widely between the Brachiaria species and planting seasons: 0.2-1.2 kg ha-1 day-1 for N; 0.01-0.07 kg ha-1 day-1 for P; and 0.13-0.8 kg ha-1 day-1 for K. However, the greatest nutrient accumulation was found for B. brizantha, followed by B. ruziziensis and then B. Convert. In the short-term, corn intercropped with Brachiaria in the season showed the largest effect on the nutrient cycling and biomass yield. The intercropping between corn and B. brizantha in the season was the best way to enhance the biomass yield and the N, P and K cycling.

Cultivation of sunflower irrigated with domestic sewage treated in Quartzarenic Neosol

The use of domestic sewage treated in irrigation as an alternative in arid regions. However, due to the high concentration of nutrients, the use these waters can soil degradation. The objective of this study was to evaluate the effect of the use of these waters on soil attributes. The experimental design was a randomized complete block design (4 x 2 x 3) in subdivided plots with four replications. The treatments consisted of three factors, four water sources in the irrigation (A1 - sewage treated by UASB reactor, A2 - treated sewage treated with anaerobic filtration, A3 - treated sewage by anaerobic filtration and A4 - water supply); two irrigation depths (L1 - equal to crop evapotranspiration and L2 - 20% higher than crop evapotranspiration) and three soil layers (0-0.2, 0.2-0.4 and 0.4-0.6 m), the three soil layers were considered as subplots. The use of water sources A1 and A2 provided lower concentrations of sodium in the saturation extract. The use of domestic sewage treated in the irrigation provided an increase in the levels of Ca2+ and Mg2+ solubles in the soil and the EC without reach it saline. Greater nutrient accumulation was verified in the shallow layer of 0-0.20 m being influenced by the effective depth of the root system as well as by the climatic conditions of the region.

Effect of temperature and photoperiod on the early development of nudibranch Diaulula punctuolata (d’Orbigny, 1837) under laboratory conditions

Temperature plays an important role in both the development and growth of marine invertebrates; furthermore, it has been observed that photoperiod significantly affects feeding, growth and larval survival. In this study we evaluated the effect of temperatures of 10° and 16°C and photoperiods of 8:16 and 16:8 on early development, hatching and larval survival in the nudibranch Diaulula punctuolata, under laboratory conditions. At 16oC/8:16, hatching occurred between 10 and 11 days post-spawning (dps), with a physiological time of 162.3 ± 10.1 degree day (d°C); while at 10°C/8:16, hatching took place between 17 and 20 dps; 200.5 ± 27.4 d°C (F = 366.6; P ˂ 0.05). The highest hatching percentage, 82.9%, was obtained at 10°C (F = 16.63; P ˂ 0.05) coinciding with environmental conditions present during the adult collection season. Larvae obtained at 16°C were larger (146.3 ± 0.8 µm) than those at 10°C (140.4 ± 0.5 µm) (F = 212; P ˂ 0.05). Nevertheless, survival time was greater at 10°C/8:16 (21 dps), which could be associated with greater nutrient accumulation during embryonic development. Both embryonic and larval development are dependents on temperature, but not on photoperiod; an increase in temperature from 10º to 16°C, reduced the chronological time required up to hatching by 45.6 ± 3.4%. Photoperiod only affected larval survival at 10°C.

Maize varieties released in different eras have similar root length density distributions in the soil, which are negatively correlated with local concentrations of soil mineral nitrogen.

Larger, and deeper, root systems of new maize varieties, compared to older varieties, are thought to have enabled improved acquisition of soil resources and, consequently, greater grain yields. To compare the spatial distributions of the root systems of new and old maize varieties and their relationships with spatial variations in soil concentrations of available nitrogen (N), phosphorus (P) and potassium (K), two years of field experiments were performed using six Chinese maize varieties released in different eras. Vertical distributions of roots, and available N, P and K in the 0–60 cm soil profile were determined in excavated soil monoliths at silking and maturity. The results demonstrated that new maize varieties had larger root dry weight, higher grain yield and greater nutrient accumulation than older varieties. All varieties had similar total root length and vertical root distribution at silking, but newer varieties maintained greater total root length and had more roots in the 30–60 cm soil layers at maturity. The spatial variation of soil mineral N (Nmin) in each soil horizon was larger than that of Olsen-P and ammonium-acetate-extractable K, and was inversely correlated with root length density (RLD), especially in the 0–20 cm soil layer. It was concluded that greater acquisition of mineral nutrients and higher yields of newer varieties were associated with greater total root length at maturity. The negative relationship between RLD and soil Nmin at harvest for all varieties suggests the importance of the spatial distribution of the root system for N uptake by maize.

Availability of nutrients, productive properties, and quality of sunflower (Helianthus annuus L.) seeds in acid soils amended with different molar ratios between Ca and Mg

Liming is indispensable in acid soils for amending acidity; however, the technique may alter the cation balance in soil and, consequently, may limit the availability and uptake of nutrients. We aimed to evaluate different molar ratios between calcium (Ca) and magnesium (Mg) on the availability of soil nutrients and their influence on the productive properties of sunflower and seed quality. The experiment was carried out in a greenhouse under two types of contrasting soils and six molar combinations of CaCO3and MgCO3 in amendment of soil acidity to raise base saturation to 70%. After incubation, soil analysis was undertaken to verify the ratios obtained and nutrient availability. Morphological and production variables were analyzed at the end of the experiment, as well as accumulation of nutrients in the achenes and their physiological quality. In spite of equal base saturation between the types of soil, there were differences in the available contents of these cations. The increase in the Ca contents limited the Mg contents to the critical level of the sunflower. This result had a negative influence on the production properties of sunflower and physiological quality. In contrast, there was a compensation of the crop with greater accumulation of nutrients in the achenes under lower yield.

Drought risk management for increased cereal production in Asian Least Developed Countries

Drought stress is a serious abiotic factor inhibiting nutrient acquisition by roots and limiting cereal crop production in Asian Least Developed Countries (LDCs). Many studies revealed that balanced fertilization can improve photosynthetic activity by stabilizing superoxide dismutase (SOD) activity, improve proline, abscisic acid (ABA) and make the crop drought tolerant with efficient root system and finally improve crop yield. To mitigate drought stress, along with the usage of resistant and efficient genotypes, soil and foliar applications of macro- and micro-nutrients are being used in Asia. According to drought sensitivity index, the efficient genotypes are found more drought-tolerant than the inefficient ones. Studies revealed that irrigation alone is not sufficient to obtain satisfactory grain yield without balanced fertilization. At drought stress, the efficient genotypes accumulate higher quantities of ABA and proline, and exhibit higher activities of SOD, as compared with inefficient genotypes through greater nutrient accumulation by their longer and thinner root systems with high efficiency. Under severe drought with low nutritional status, the rate of photosynthesis, particularly water-use efficiency (WUE) increases in the efficient genotypes than in the inefficient ones. Consequently, these physiological and morphological parameters result in better yield performance by efficient use of water. Under drought, soil application of NPK along with foliar application of zinc (Zn), boron (B) and manganese (Mn) increase grain yield as well as micronutrients concentration of the grain. The rate of photosynthesis, pollen viability, number of fertile spikes, number of grains per spike, and WUE are increased by late foliar application of these micronutrients. This indicates that, by increasing WUE foliar application of Zn, B and Mn at booting to anthesis can reduce the harmful effects of drought that often occur during the late stages of cereal production in Asian LDCs. Therefore, it can be concluded that soil application of Zn, B and Mn in early stage combined with foliar application in late stage, especially at the flowering stage, is a promising approach to alleviate drought stress. Another attractive environmental friendly approach is to select efficient and drought tolerant genotypes with a more efficient root system. These findings are of high relevance for farmers׳ practices, the extension service and fertilizer industry to mitigate the drought stress in Asian LDCs. A few recommendations are made for extension of scientific knowledge to find more scope in support of mitigating drought situation.

Macronutrient uptake, accumulation and export by the irrigated 'vitória' pineapple plant

The nutritional state of the pineapple plant has a large effect on plant growth, on fruit production, and fruit quality. The aim of this study was to assess the uptake, accumulation, and export of nutrients by the irrigated 'Vitória' pineapple plant during and at the end of its development. A randomized block statistical design with four replications was used. The treatments were defined by different times of plant collection: at 270, 330, 390, 450, 510, 570, 690, 750, and 810 days after planting (DAP). The collected plants were separated into the following components: leaves, stem, roots, fruit, and slips for determination of fresh and dry matter weight at 65 ºC. After drying, the plant components were ground for characterization of the composition and content of nutrients taken up and exported by the pineapple plant. The results were subjected to analysis of variance, and non-linear regression models were fitted for the significant differences identified by the F test (p&lt;0.01). The leaves and the stem were the plant components that showed the greatest accumulation of nutrients. For production of 72 t ha-1 of fruit, the macronutrient accumulation in the 'Vitória' pineapple exhibited the following decreasing order: K &gt; N &gt; S &gt; Ca &gt; Mg &gt; P, which corresponded to 898, 452, 134, 129, 126, and 107 kg ha-1, respectively, of total accumulation. The export of macronutrients by the pineapple fruit was in the following decreasing order: K &gt; N &gt; S &gt; Ca &gt; P &gt; Mg, which was equivalent to 18, 17, 11, 8, 8, and 5 %, respectively, of the total accumulated by the pineapple. The 'Vitória' pineapple plant exported 78 kg ha-1 of N, 8 kg ha-1 of P, 164 kg ha-1 of K, 14 kg ha-1 of S, 10 kg ha-1 of Ca, and 6 kg ha-1 of Mg by the fruit. The nutrient content exported by the fruits represent important components of nutrient extraction from the soil, which need to be restored, while the nutrients contained in the leaves, stems and roots can be incorporated in the soil within a program of recycling of crop residues.

Estado nutricional de pinheira sob adubação orgânica do solo

No período de agosto de 2009 a julho de 2010 foi desenvolvido um experimento em um pomar de pinheira (Annona squamosa L.), no município de Remígio, PB com o objetivo de avaliar os teores de macro e micronutrientes no tecido foliar das plantas em solo com esterco bovino e cama de frango. Os tratamentos foram distribuídos em blocos casualizados, com parcelas subdivididas no tempo, com três repetições e duas plantas por parcela, em esquema fatorial 2 × 5 × 2, referente a duas fontes de matéria orgânica de origem animal (esterco de bovino e cama de frango), cinco doses de matéria orgânica em volume (0,0; 3,5; 5,3; 7,1 e 8,9%) e duas épocas de avaliação das plantas aos 36 e 48 meses após o transplantio. As doses de matéria orgânica foram definidas com base no teor de matéria orgânica de cada fonte. Com exceção de magnésio e zinco, as fontes de matéria orgânica não diferiram estatisticamente sobre os teores dos demais nutrientes na matéria seca foliar das plantas. A maior acumulação de nutrientes na matéria seca das folhas da pinheira ocorreu na amplitude das doses entre 6,01 e 8,65% de matéria orgânica.

Crescimento e absorção de nutrientes pelo algodoeiro e pela mamoneira adubados com gliricídia e esterco

As quantidades de esterco disponíveis nas propriedades não são suficientes para adubar as áreas agrícolas na região semiárida do Brasil. Além disso, o esterco apresenta, em geral, baixa qualidade e pode causar imobilização de nitrogênio do solo. Sendo assim, os adubos verdes, como as ramas de gliricídia ou a sua mistura com esterco, podem ser boa alternativa para aumentar a disponibilidade e a qualidade de adubos orgânicos. O crescimento inicial e a absorção de nutrientes pelo algodoeiro e pela mamoneira, adubados com esterco e/ou gliricídia, foram medidos em dois cultivos consecutivos, em casa de vegetação, utilizando-se os tratamentos: testemunha; incorporação de 20 t ha-1 de esterco; incorporação de 20 t ha-1 de folhas de gliricídia; e incorporação da mistura de 10 t ha-1 de esterco e de 10 t ha-1 de gliricídia. O tratamento com a incorporação de gliricídia apresentou maior crescimento das plantas de algodão e de mamona, tal como a maior e mais rápida disponibilização de N mineral e o maior acúmulo de nutrientes, com recuperações aparentes de N, P e K, significativamente superiores às dos demais tratamentos. O esterco não aumentou a disponibilidade de N no solo, mas sua mistura com a gliricídia aumentou a disponibilidade de N, P e K do solo em relação à testemunha, tratando-se de prática promissora capaz de melhorar a qualidade do esterco.

Plantas de cobertura e seus efeitos sobre o feijoeiro em plantio direto

O objetivo deste trabalho foi estimar o rendimento de matéria fresca, matéria seca e o acúmulo de nutrientes da fitomassa produzida por milheto (Pennisetum americanum (L.) Leek), sorgo (Sorghum bicolor (L.) Moench), milho (Zea mays L.), mucuna-preta (Stizolobium aterrimum) e feijão-de-porco (Canavalia ensiformis (L.) DC.), em cultivo exclusivo e consorciado, e seus efeitos sobre o feijoeiro (Phaseolus vulgaris L. cv. Carioca) em plantio direto. Os tratamentos consistiram no cultivo exclusivo das espécies e nos consórcios das gramíneas com as leguminosas. Utilizou-se o delineamento experimental em blocos casualizados, com quatro repetições. O sorgo em cultivo exclusivo apresenta maior produtividade de matéria fresca e, juntamente com o milheto exclusivo e o consórcio milheto e mucuna-preta, maior produtividade de matéria seca. Ocorre maior acúmulo de nutrientes no milheto exclusivo e consorciado com mucuna-preta. Posteriormente, realizou-se o plantio direto do feijoeiro, cujo rendimento de grãos é influenciado pelas diferentes palhadas das plantas de cobertura no sistema plantio direto, sendo mais afetado pela espécie produtora de palha do que pela sua forma de cultivo.

Mycorrhizal and common root-rot infection, and nutrient accumulation in barley grown on breton loam using N from biological fixation or fertilizer

This paper presents soil biological data from a study on the functioning of three soil-plant systems on a Gray Luvisol in Cryoboreal Subhumid central Alberta. The systems were (1) an agroecological 8-year rotation, (2) a continuous grain system, both established in 1981, and (3) a classical Breton 5-year rotation established in 1930. The objectives were to (1) determine whether changes in vesicular-arbuscular mycorrhizae (VAM) populations occurred in soil under these cropping systems, (2) discover whether these cropping systems and/or VAM infection influenced the incidence of common root rot (Bipolaris sorokiniana), and (3) use nutrient translocation indices to test the hypothesis that soil quality influences non-specific physiological conditions in barley (Hordeum vulgare L.). VAM fungal propagules in soil samples and VAM infection under controlled conditions were significantly affected by the cropping system. VAM infection accounted for more than 85% of the variability in grain yield, plant biomass yield, and plant uptake of K, S, Ca, Fe, and Zn under controlled conditions. Backward-elimination regression analyses showed that under these conditions of high available P, plant P uptake was governed by the quantity of extractable P in the soil (r2=0.82); the VAM infection contributed practically nothing when combined with available P (R2=0.84). Neither VAM infection nor the cropping system were related to the B. sorokiniana infection in the barley. The growth of B. sorokiniana was equal, and its sporulation superior, when grown on residues of the non-host fababean (Vicia faba L.), compared with growth on residues of barley. Higher translocation of plant nutrients to the grain in the agroecological compared with the continuous grain treatments suggested that VAM and/or the soil history affected plant physiology, possible through hormonal effects. Superior barley yields in the agroecological compared with the continuous grain treatments were partly due to increased VAM colonization, greater nutrient accumulation and translocation to the grain, but not to a reduced disease incidence. These results demonstrate the benefits of a holistic systems approach while studying biological interactions involving plants and groups of soil microorganisms.