Orchard Fertilization Research Articles

Path Planning Algorithm of Orchard Fertilization Robot Based on Multi-Constrained Bessel Curve

Path planning is the core problem of orchard fertilization robots during their operation. The traditional full-coverage job path planning algorithm has problems, such as being not smooth enough and having a large curvature fluctuation, that lead to unsteady running and low working efficiency of robot trajectory tracking. To solve the above problems, an improved A* path planning algorithm based on a multi-constraint Bessel curve is proposed. First, by improving the traditional A* algorithm, the orchard operation path can be fully covered by adding guide points. Second, according to the differential vehicle kinematics model of the orchard fertilization robot, the robot kinematics constraint is combined with a Bessel curve to smooth the turning path of the A* algorithm, and the global path meeting the driving requirements of the orchard fertilization robot is generated by comprehensively considering multiple constraints such as the minimum turning radius and continuous curvature. Finally, the pure tracking algorithm is used to carry out tracking experiments to verify the robot’s driving accuracy. The simulation and experimental results show that the maximum curvature of the planned trajectory is 0.67, which meets the autonomous operation requirements of the orchard fertilization robot. When tracking the linear path in the fertilization area, the average transverse deviation is 0.0157 m, and the maximum transverse deviation is 0.0457 m. When tracking the U-turn path, the average absolute transverse deviation is 0.1081 m, and the maximum transverse deviation is 0.1768 m, which meets the autonomous operation requirements of orchard fertilization robots.

Selection of Spectral Parameters and Optimization of Estimation Models for Soil Total Nitrogen Content during Fertilization Period in Apple Orchards

The rapid and accurate diagnosis of nitrogen content in apple orchard soil is of great significance for the rational application of nitrogen fertilizer in orchards to improve apple yield and quality. An apple orchard in Shuangquan Town, Changqing District, Jinan City, Shandong Province, was taken as the experimental area. The optimal method for extracting spectral characteristic bands and screening spectral characteristic indices (SCIs) of soil total nitrogen (TN) for independent and comprehensive fertilization periods was explored. Independent and comprehensive soil TN content estimation models were constructed and optimized for each and the entire fertilization period, respectively. The results show that compared with the correlation coefficient method, stepwise multiple linear regression (SMLR) performs better in extracting hyperspectral characteristic bands of soil TN content. It helps to achieve a higher modeling accuracy, smaller root mean square error (RMSE), and is more conducive to avoiding the influence of multicollinearity of model variables. The sensitive areas of soil TN content in the SCI do not undergo significant changes due to different fertilization periods. Among them, the ratio spectral indices (RSIs) are in the range of 800–900 nm, 1900–1950 nm, and 2200–2300 nm, while the sensitive areas of the difference spectral index (DI) and Normalized difference spectral index (NDSI) are in the range of 1900–1950 nm and 2200–2300 nm. The combination of SCI and characteristic bands significantly improves the prediction accuracy of soil TN estimation models. The independent and comprehensive estimation models for each fertilization period based on the BP (back propagation) neural network optimized by the Mind Evolution Algorithm (MEA-BPNN) can achieve a more stable and accurate estimation of soil TN. Finally, using soil spectral characteristic bands selected through continuum removal (CR) transformation and SMLR, combined with SCI, the model based on the MEA-BPNN (CR-SCI-MEA-BPNN) has the best prediction performance. The modeling determination coefficients R2 for each fertilization period reached 0.94, 0.95, 0.92, and 0.94, respectively, with RMSE of 0.0032, 0.0024, 0.0035, and 0.0027. The R2 and RMSE of the modeling and validation set of the entire fertilization period comprehensive model are 0.899, 0.0038, and 0.89, 0.0041, respectively. The results of this article provide technical support for promoting the timely monitoring of soil TN content and guiding rational fertilization in apple orchards.

Storm-induced nitrogen transport via surface runoff, interflow and groundwater in a pomelo agricultural watershed, southeast China

The storm-induced export of nitrogen (N) from agricultural watersheds significantly impacts aquatic ecosystems, yet the mechanisms of source supply and transport behind N species remain unclear. Here, we investigated the hydrological factors influencing the timing and magnitude of river N species export in a Chinese pomelo agricultural watershed. We conducted continuous observations of watershed hydrology, N species, and their isotopic ratios along a soil-groundwater-river continuum during two storm events in 2018–2019. We found the export flux of river NO3–N covers ∼80% of the total N flux during storms, and the rest for other N species. Our results further revealed distinct pathways and timing of N transport among different N species, especially between ammonium N (NH4–N) and nitrate N (NO3–N). NH4–N in stormflow predominantly originates from sewage and soil leachate, rapidly transported via surface runoff and interflow. Orchard fertilization (contributed 41–56% based on SIAR analysis) was the major source of river NO3–N, which underwent initial dilution via surface runoff and subsequently became enriched through delayed discharge of soil leachate and groundwater. The variations in timing and magnitude of N transport between storms can be explained by antecedent conditions such as precipitation, soil N pools, and storm size. These findings emphasize the hydrological controls on N export from agricultural watersheds, and highlight the variations in source supply and transport pathways among different N species. The insights gained from this study hold significance for managing agricultural pollution and restoring impaired aquatic systems.

Macro and Microelements in Leaves of ‘Meredith’ Peach Cultivar Supplied with Biochar, Organic and Beneficial Biofertilizer Combinations

The content of macro and microelements in the leaves of peach trees treated with biochar, organic fertilization and microorganisms in the field experiment was tested. The experiment was carried out in accordance with the integrated fruit production methods at the NIHR Experimental Orchard in Dąbrowice, from 2015 to 2017. The trees were grafted on P. persica Mandżurska rootstock and planted in the spring of 2013. In 2014, the following products were applied around the trees and mixed into the topsoil: biochar at a dose of 1.6 kg/tree (2000 kg/ha); biochar at a dose of 1.6 kg/tree used together with microorganisms—bacteria Pseudomonas fluorescens, Pantoea and arbuscular mycorrhizal fungi—Glomus caledonium, Glomus intraradices and Glomus coronatum; biochar at a dose of 1.6 kg/tree applied together with Florovit NPK organic fertilizer at a dose of 0.2 kg/tree; Florovit NPK; microorganisms—bacteria Pseudomonas fluorescens, Pantoea and arbuscular mycorrhizal fungi—Glomus caledonium, Glomus intraradices and Glomus coronatum; Florovit NPK organic fertilizer with the same microorganisms; and an untreated control. The average results showed that, compared to the control, the biochar increased the nitrogen content in the leaves by 6%. All experimental combinations increased the content of P and K in the leaves. The most effective at increasing the content of phosphorus in leaves—by 48%—was Florovit. The greatest increase in potassium was after the use of biochar with Florovit—by 38%. The magnesium content ranged from 0.49 to 0.59 g/100 g DW. The highest content of Mg was found in the leaves after the application of biochar with Florovit, and the lowest after the use of biochar alone. The leaves of the trees fertilized with the Florovit organic fertilizer had the lowest calcium content, while the highest calcium content was found in combination with trees treated with biochar only. The use of biochar alone did not increase the content of boron in the leaves compared to the control. In all other combinations, a higher amount of boron was found. The highest—18% more than the control of this microelement had leaves where biochar and Florovit were used. Trees treated with biochar and microorganisms accumulated the least copper in the leaves, while the highest content of this element was found in the combination where biochar fertilization was applied together with Florovit. Lower iron concentrations in peach leaves were found as a result of applying microorganisms, microorganisms with the organic fertilizer and biochar, relative to organic fertilization and the control combination. Trees where only microorganisms were applied to the soil had the least manganese and zinc in the leaves. The accumulation of manganese in the leaves was most favored by fertilization with biochar together with microorganisms, and the zinc content was the highest after the use of biochar alone. In general, studies have shown that a small dose of biochar alone or biochar together with organic fertilizer is a very effective method of feeding peach trees. More research is needed on the use of microorganisms and methods of their application with various products used in orchard fertilization.

Effect of macronutrient fertilization on olive oil composition and quality under irrigated, intensive cultivation management.

Intensive olive (Olea europaea L.) orchards are fertilized, mostly with the macronutrients nitrogen (N), phosphorus (P) and potassium (K). The effects of different application levels of these nutrients on olive oil composition and quality were studied over 6 years in a commercial intensively cultivated 'Barnea' olive orchard in Israel. Oil quality and composition were affected by N, but not P or K availability. Elevated N levels increased free fatty acid content and reduced polyphenol level in the oil. Peroxide value was not affected by N, P or K levels. The relative concentrations of palmitoleic, linoleic and linolenic fatty acids increased with increasing levels of N application, whereas that of oleic acid, monounsaturated-to-polyunsaturated fatty acid ratio and oleic-to-linoleic ratio decreased. These results indicate that intensive olive orchard fertilization should be carried out carefully, especially where N application is concerned, to avoid a decrease in oil quality due to over-fertilization. Informed application of macronutrients requires leaf and fruit analyses to establish good agricultural practices, especially in view of the expansion of olive cultivation to new agricultural regions and soils. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Essential Role of Potassium in Apple and Its Implications for Management of Orchard Fertilization.

K (K) is of paramount importance for apple (Malus × domestica Borkh.), not only for tree growth and development but also for the size and quality of fruit yield. The apple plant’s demand for K varies, along with the progression of phenological phases, during the growing season. The K demand peaks during ripening of fruits featuring relatively high concentration of K comparable to that of the leaves. The mainstream method of apple tree K fertilization is through application of the fertilizer to the soils to improve K uptake by the roots. The bioavailability of K depends on assorted various factors, including pH, interaction with other nutrients in soil solution, temperature, and humidity. An important role in making the K from soil available for uptake by plants is played by plant growth-promoting microorganisms (PGPM), and the specific role of the PGPM is discussed. Advantages of fertigation (the combination of irrigation and fertilization) as an approach include allowing to balance application rate of K fertilizer against its variable demand by plants during the growing season. Excess K in the soil leads to competitive inhibition of calcium uptake by plants. The K-dependent deficiency of Ca leads to its predominant channeling to the leaves and hence to its decline in fruits. Consequently, the apple fruits affected by the K/Ca imbalance frequently develop physiological disorders in storage. This emphasizes the importance of the balanced K application, especially during the last months of the growing season, depending on the crop load and the actual K demand. The potential use of modern approaches to automated crop load estimation through machine vision for adjustment of K fertilization is underlined.

Organic fertilization and crop load in yield and quality of organic nectarines in Italy

Abstract Organic fertilization in orchards aims at increasing soil fertility, at impacting plant productivity and environmental sustainability. This study aimed at verifying the effects of organic fertilization and fruit load on two nectarine cultivars with high and low fruit loads. The experiment was carried out in an orchard under organic management in Fratta Terme, Po valley, in northeastern Italy. Nectarine cultivars Big Top and Carene, implemented in 2017 and grafted onto GF677, were used. Three levels of compost (0, 20 and 40 t dw ha-1) were combined with two fruit loads (low and high) to set up a factorial experimental design with two factors and four randomized replicates. Compost was incorporated at 20 cm depth. The following parameters were evaluated: nitrate- and ammonium- N concentrations in soil at 20 - 40 cm depth, macro and micronutrients in leaves, tree yield, number of fruits, fruit mass and diameter, soluble solids and pulp firmness. The supply of compost enhanced nitrate-N release in soil. In both cultivars, macro- and micronutrient concentrations in leaves were not affected by organic fertilization or fruit load, except for iron, which increased as a consequence of the compost supply. Low crop load induced higher fruit size in both varieties, a fact that was observed after pit hardening. However, the organic fertilization rate did not influence tree yield, fruit mass and soluble solids.

The application of biomodified fertilizers as a way to increase the effective fertility of orchard soils

The crucial trend in the intensification of gardening is the use of agrochemicals, including the systematic application of mineral fertilizers, regulated by the production flow chart of fruit products. Technological pressure on the soil causes aggravating the ecological problem of loss of the fertility level in the conditions of the orchard monoculture. The search for sustainable and environmentally effective approaches to solving the problem of managing fertility factors is aimed at studying the effects of biological and biomodified fertilizers. The changes in the main indicators of the effective fertility of the structural-metamorphic agrosem in the conditions of the orchard monoculture with the application of biomodified organo-mineral fertilizer were studied in dynamics. The prolonged effect of organo-mineral fertilizer on increasing the content of the main indicators of effective fertility in the soil was determined six years after application. The use of biomodified organo-mineral fertilizer in the orchard fertilization system is considered as an element of an integrated strategy for the management of orchard soil fertility.

Present Situation, Existing Problems and Recommendations for Orchard Fertilization Technology

Present Situation, Existing Problems and Recommendations for Orchard Fertilization Technology

Nitrogen fertilization rates in a subtropical peach orchard: effects on tree vigor and fruit quality.

Nitrogen is a key component of crop production and is commonly related to increases in yield and fruit size. The N fertilization rates used for low-chill peach cultivars were adapted from other peach production regions, where environmental and soil conditions are different. The growth and production as well as the effect on fruit physical and compositional attributes of two low-chill peach cultivars-'TropicBeauty' (TB) and 'UFSharp' (UFS)-with five different N fertilization rates (0 (N0), 45 (N1), 90 (N2), 179 (N3) and 269 (N4) kg ha-1 applied each year from 2011 to 2017) were examined. Peach trees under higher N rates had higher pruning weights compared to the lower N0 or N1 rates. Yield was only affected in 2017 for the two cultivars tested. Physical attributes were inconsistently affected by N. Fruit from the higher N rates had lower a* value (more green) than fruit from the trees under low or zero N. While fruit firmness was not affected by N, fruit from trees under zero/low N had higher total soluble solids in some years. Considering that N is recycled in the trees, being retained and reused each season to resume growth, it is important to address peach orchard fertilization based on peach tree N status. The results of this experiment show that an increase in N beyond what is required for tree maintenance does not increase yield. In addition, reducing N does not strongly affect fruit quality, although the color and soluble solids results suggest that lower N rates may advance fruit maturation. © 2019 Society of Chemical Industry.

Wolfberry tree dual-model detection method and orchard target-oriented fertilization system based on photoelectric sensors

Orchard target-oriented fertilizing with on-board sensor technology can improve fertilizer efficiency and reduce environmental pollution. Photoelectric sensors are widely used for object detection because of their low cost and fast response time. This paper presents a Wolfberry tree dual-model detection method and the design of an orchard target-oriented variable-rate fertilization system based on photoelectric sensors. The dual-model detection method includes the Trunk Detection Model (TDM) and Canopy Detection Model (CDM), which can be applied for Wolfberry orchards at the green cluster and mature stages, respectively. A target-oriented fertilization system was designed using the dual-model method, and tested in the lab and Chinese Wolfberry orchard. The laboratory test results showed that the average center offset distances on the condition of detecting trunks, continuous canopies, and discontinuous canopies were 4.1 cm, 9.1 cm and 13.1 cm, respectively. The system could ignore the signals from canes when their diameters were less than 16 mm, and also could determine the gaps within a tree when they were less than 21 cm. The orchard test results showed that the system accomplished target-oriented fertilization 95 times for 92 trees at the mature stage. The results indicated that the dual-model detection method could be used for Wolfberry trees or other trees with similar canopy changes at different growth stages. Keywords: orchard fertilizer, target-oriented fertilization, variable rate fertilization, photoelectric sensor, wolfberry orchard DOI: 10.25165/j.ijabe.20181104.3614 Citation: Yang S, Zhai C Y, Long J, Zhang B, Li H Z. Wolfberry tree dual-model detection method and orchard target-oriented fertilization system based on photoelectric sensors. Int J Agric & Biol Eng, 2018; 11(4): 65-73.

Alternative Fertility Management for Establishing New Apple Orchards in the Mid-Atlantic

In the Mid-Atlantic, mineral nitrogen (N) fertilizers are applied in high-density apple (Malus ×domestica Borkh.) orchards to increase tree vegetative growth and achieve earlier fruiting. However, when applied in excess of plant needs, N fertilizer applications are an unnecessary expense and may lead to N leaching and groundwater pollution. Therefore, it is necessary to develop orchard fertilization programs that simultaneously provide adequate crop nutrition and minimize N loss into the environment. Nitrogen was applied in each of 3 years to newly planted ‘Red Delicious cv Schlect’/‘M.26’ trees at 67 kg N/ha/year in six fertilizer treatments: 1) two equal applications of granular calcium nitrate [Ca(NO3)2]; 2) chicken litter compost; 3) yardwaste compost; 4) a combination of chicken litter compost and granular Ca(NO3)2 with equal amounts of N from each fertilizer; 5) a combination of yardwaste compost and granular Ca(NO3)2 with equal amounts of N from each fertilizer; and 6) fertigation which consisted of eight weekly applications of solubilized Ca(NO3)2. Nonfertilized trees served as the control. In the third year of this experiment, the two chicken litter compost treatments had the greatest soil extractable P, the yardwaste compost treatment had the greatest soil extractable K, both full-rate compost treatments had greater soil extractable Mg than the other treatments, and all four compost treatments had greater soil extractable Mn than the treatments without compost. The four compost treatments also had greater soil extractable Ca and B than treatments without compost. By the third year of the experiment, the four compost treatments also had greater soil organic matter (OM) and soil C (with the integrated chicken litter compost treatment having similar soil C to the other treatments). Potentially mineralizable nitrogen and soil microbial biomass were similar among the treatments over the course of this experiment. The full rate chicken litter compost treatment and both yardwaste compost treatments had greater soil microbial respiration in 2015. The fertigation treatment performed similarly to the treatment where Ca(NO3)2 was applied as a granular product to the soil. Treatment differences found for the soil properties did not translate to increased tree size or leaf N content, suggesting that the trees were able to acquire sufficient N from the soil under all of the treatments. Our results suggest that applying fertilizers to fine textured soil with relatively high OM may not increase apple tree growth or productivity within the first 3 years after planting. In addition, compost applications can improve many soil properties, but these differences may not result in improved orchard productivity within 3 years.

Elemental accumulation in mango (Mangifera indica L.) as a function of maturity stage and variety

ABSTRACTInformation about the nutritional status of a plant is a basic prerequisite for its adequate nutrition and is crucial to achieve high-yield productivity. Assessing the annual amount of nutrient that a tree needs to absorb in order to successfully complete a vegetative and reproductive growth is a fundamental step for developing rational fertilization in orchards. We are unaware of any report describing macro- and micronutrient dynamics in fruit at different growth stages of mango. Seven cultivars of mango (Dashehari, Langra, Mahmood Bahar, Menka, Sabri, Sundar Langra and Zardalu) were selected for the study. Different macronutrients such as nitrogen, phosphorus, potassium, calcium and magnesium (N,P, K, Ca, and Mg) and micronutrients such as iron, manganese, zinc and copper (Fe, Mn, Zn, and Cu) were analyzed at four growth stages, namelymarble stage, prestone formation stage, stone hardening stage and harvest stage. There was a significant variation in nutrient content of fruits throughout the developmental stages irrespective of cultivars. There was no definite trend of nutrient variation among cultivars but in general, most of the nutrients like N, P, K, Mg, Mn, Zn, and Cu were the highest at the marble stage, and Ca and Fe at the stone hardening stage.

‘FUJI’ APPLE TREE RESPONSE TO PHOSPHORUS FERTILIZATION

ABSTRACT The aim of this work was to evaluate the effects of orchard fertilization with increasing rates of phosphorus (P) on yield and critical levels of P in the soil and in the leaf of ‘Fuji’ apple trees. The experiment was conducted in São Joaquim, state of Santa Catarina, southern Brazil, from 2010 to 2015, in an Inceptisol soil. The three apple orchards were planted in 2004 with the Fuji cultivar grafted on Marubakaido/ M9 rootstock and grown under a high-plant-density system (1984 trees ha-1). Annual fertilizer levels of 0, 40, 80, 120 and 160 kg ha-1 of P2O5 (as triple superphosphate) were applied to the soil surface, without incorporation, in a randomized block design with five replicates. In the first and last years (2011 and 2015), soil samples were collected from 0-10, 10-20 and 0-20 cm layers and the available P content was analyzed. Annually, whole leaves were collected and analyzed for P content. The number and weight of fruits per tree and hfruit yield were also evaluated. Application of P increased the content of available P in the soil, but this increase was not accompanied by increased leaf P content nor by increased fruit yield. This suggests that, in soils with medium to high content of organic matter and well fertilized with P before planting, there is no response of apple trees for P reapplication in the 10 subsequent years.

Effect of Cover Crop Species and Liquid Manure Application Rate on Green Manure Production, Leaf Mineral Content, Fruit Quality and Soil Chemical Properties in Pear Orchard

Cover cropping and liquid manure application are considered as effective ways to replace the use of chemical fertilizer in orchard. This study was conducted to investigate the effect of cover crop species and liquid manure application rate on green manure production, leaf mineral content, fruit quality and soil chemical properties in pear orchard. The treatments include rye and hairy vetch as cover crops, two liquid manure application levels based on N and <TEX>$K_2O$</TEX> requirement on each cover crop species, and chemical fertilizer as control. Green manure production was higher in hairy vetch than in rye. K content of pear leaves and soil exchangeable K content increased in N based liquid manure application treatments. The yield was higher in rye + liquid manure and fertilizer treatments, and fruit quality was not different between the treatments. Taking all of these into account, rye + <TEX>$K_2O$</TEX> requirement-based liquid manure application is recommended in pear orchard for not only sufficient nutrient supply but also prevention of any problem related with soil <TEX>$K_2O$</TEX> accumulation in pear orchard in long-term perspective.

Assessment of carbon footprint and energy performance of the extra virgin olive oil chain in Umbria, Italy

The cradle to grave carbon footprint (CF) and energy footprint (EF) analysis of extra virgin olive oil (EVOO) produced in the Province of Perugia (Umbria, Italy) is assessed. In this study, olive orchard cultivation, EVOO extraction, bottling, packaging, storage at −18°C and distribution in the main importing countries were studied from a life cycle assessment perspective, with the main objective of identifying the processes with the largest environmental impacts. The selected functional unit was 1L of EVOO, packaged for distribution. Inventory data was gathered mainly through both direct communication using questionnaires and direct measurements. To determine the CF the ISO/TS 14067:2013 was followed while the EF was evaluated according to ISO standards 14040 and 14044. Results showed that the most impacting process is the distribution, mainly due to the choice of employing air transport. The main other hot spots identified were the olive orchard fertilization, EVOO freezing during its storage at the olive mill factory and the manufacture of glass bottles. Suggested improvement opportunities included shifts in the EVOO transportation policy, the introduction of lighter glass bottles in the bottling process, the use of cooling agent with lower global warming potential and the employment of biodiesel in the farming machineries.

Effect of fruit-load on the growth, absorption, and partitioning of inorganic nutrients in young ‘Fuyu’ persimmon trees

Tree growth and the increase in inorganic nutrients during a growing season were studied in 3-year-old, container-grown ‘Fuyu’ persimmon trees with different levels of fruit-load. Fruit-load was varied by adjusting the leaf–fruit ratio to 10, 20, 30, and 60 on July 5. Some trees were completely defruited. The whole trees were harvested on November 5 of that year, and increases in dry weight and inorganic elements in different tree parts during the season were measured. A lower leaf–fruit ratio resulted in a higher yield but also decreased fruit weight, soluble solids, and fruit color. Dry weight of the aerial woods and root increased significantly with a greater ratio. However, total dry weight including the fruits was higher in the lower ratio trees than in the higher ratio trees; the weight of a tree that maintained the ratio of 10 was 35% higher than a tree without fruit. Fruits accounted for 62% of total dry weight when the ratio was 10 and 27% when the ratio was 60. The leaf–fruit ratio did not significantly alter the total increase in P, K, Ca, and Mg content. N tended to decrease with an increasing leaf–fruit ratio. Of the total increases of N, P, and K during the season, the fruits accounted for 30%, 50%, and 54% at the ratio of 20, respectively, and the percentages increased to 44, 81, and 74 at the ratio of 10. The inorganic element content in the aerial woods and root tended to increase with greater ratios, especially in the root. When trees were defruited, N and K increases in the root accounted for 44% and 35% of the total increase, respectively. These results indicated that persimmon orchard fertilization programs with different fruit-load levels should accommodate the proportion of nutrients partitioned to fruits that are removed permanently from the tree.

Efeito da adubação com boro e esterco bovino sobre a produtividade da figueira e as propriedades químicas do solo

O objetivo deste trabalho foi verificar o efeito da adubação da cultura da figueira com boro e esterco bovino sobre a produtividade de figos verdes e as propriedades químicas do solo. Os tratamentos foram cinco doses de ácido bórico (0, 20, 40, 60 e 100g planta-1) combinadas com dois níveis de adubação de esterco (sem esterco e 10kg de esterco/planta). O delineamento experimental foi o de blocos casualizados em esquema de parcelas subdivididas e quatro repetições. A adubação com ácido bórico não afetou a produtividade de figos, enquanto que o esterco bovino aumentou-a. Os teores de fósforo e potássio no solo aumentaram significativamente e o teor de alumínio diminuiu significativamente em função da adubação com esterco bovino. O teor de B no solo, extraído pelo método da água quente, aumentou linearmente em função das doses de ácido bórico.

Improved Orchard Establishment of Asimina triloba Seedlings on Acid Soils Supplemented with Calcium Sulfate

Asimina triloba (L.) Dunal (pawpaw), a deciduous tree indigenous to the eastern U.S., is being considered as a potential new fruit crop. The difficulty in establishing transplanted pawpaw seedlings has been identified as an important research need for successful cultivation of this species. We have addressed the possible benefits of soil-applied CaSO4 in establishing pawpaw seedlings on acidic, low-Ca orchard soil. Two-year-old seedling rootstocks were planted at a spacing of 1.5 m (within rows) × 5.5 m (between rows), and trickle-irrigated (with N, P, and K) for two growing seasons. Before planting, CaSO4 was applied at rates of 0, 11, and 22 t/ha and incorporated to a depth of 15 cm. Seedling trunk cross-sectional area (TCA) growth increased with increasing CaSO4 application. After the first season, increases in TCA averaged 27% and 44% greater with CaSO4 treatments (11 and 22 t/ha, respectively), as compared to the 0 t/ha treatment. This effect was accentuated by the end of the second season. Average qualitative ratings (based on seedling vigor and appearance) were also improved with CaSO4 treatment. These findings indicate that establishment of pawpaw seedling rootstocks may be improved with Ca fertilization in orchards of low-Ca status. Additional data, including seedling dry matter accumulation, will be presented.

Nitrogen fertilization management in orchards to reconcile productivity and environmental aspects

Nitrogen fertilization in orchards of Emilia-Romagna Region, (Italy) was based in the past on excessive, not split, applications often supplied late in winter; the NUE (Nitrogen Use Efficiency) was therefore low and the risk of nitrate leaching was high. This paper summarizes the studies conducted in the last 10 years at the Department of Horticulture and Forestry of the University of Bologna aimed to develop a more rational use of nitrogen in orchards and vineyards. Root escavation of mature trees revealed that the use of localized irrigation (drip or microjet) causes a concentration of roots in the area wetted by the emitters. In such a situation, band applications of N to the tree row may allow a reduction of amounts of N fertilizer, while widespread applications, especially if the orchard soil is tilled, lead to an accumulation of nitrates in the alley. Results of several field trials where increasing N rates were applied indicate that the kind of response to N supply depends on the presence in soil of natural sources of nitrogen. This fact clearly stresses the necessity of evaluate the N status of an orchard before N fertilization. Rapid estimation of leaf chlorophyll by portable instruments is a promising index of leaf N concentration, only provided that calibration is made for each cultivar. A method, currently under testing in orchards and vineyards of Emilia-Romagna, is proposed here to adjust N fertilizer rates to the demand of the crop and to the level of available N in soil as determined in soil or soil solution samples.