Long-term studies on ground management in rainfed olive orchards

Two decades of research on soil management in rainfed olive graves, encompassing four experimental ftelds, one of which took eighteen years of continuous assessment, allowed comparative evaluation of severa! treatments including conventional tillage, residual herbicides, post-emergence herbicides, covers of natural vegetation (fertilized and unfertilized), sown covers managed as green manures and incorporated into the soil, or shredded and kept in the ground as a mulch, and sown covers of self-reseeding pasture legumes. This series of studies allowed showing that a better contrai of the herbaceous vegetation improves olive growth and yield and a greater development of the herbaceous vegetation improves severa! indicators of the soil fertility, which creates a great ambiguity. However, a large set of advantages comes from the use of early-season self-reseeding annual legumes. These plants presenta very short growing cycle and develop asynchronously with the trees (in winter, during the resting period of olive), showing reduced competition for water, allowing high productivity even in rainfed conditions. Additionally, they protect the soil from erosion ali year round, with live vegetation during winter anda mulch of dead vegetation during the summer, improve soil fertility, including the increase of soil organic matter, and are able to ftx nitrogen improving the nitrogen nutritional state of the trees.info:eu-repo/semantics/publishedVersio

Evaluación de la disponibilidad de N en suelo en pastos biodiversos ricos en leguminosas mediante el cultivo de plantas nitrófilas dentro de la dehesa

Biodiverse legume-rich pastures (BLRP) have been recommended for extensive animal production since they can improve productivity and pasture quality. However, the consequences for the N balance within the agro-system, due to the increase in biological N 2 fixation, must be monitored. A field trial was carried out to evaluate the soil N availability in a BLRP in comparison with an adjacent unsown pasture. The field experiment consisted of growing tufts of nitrophilic species (turnip, Brassica campestris and rye, Secale cereale) in the pastures rounded by PVC rings. Soil inorganic-N levels were monitored during a period of one year. The potentially available soil N was determined by growing ryegrass (Lolium multiflorum) in a pot experiment and carrying out several chemical extraction methods. The mean values of N recovered by field-grown turnip and rye were, respectively, 30.6 and 31.1 kg ha–1 in BLRP, not statistically higher than that recovered in the unsown pasture. This is consistent with the very low levels of soil inorganic-N observed both in BLRP and the unsown pasture. Nitrogen recovered by ryegrass grown in pots was significantly higher in the soil collected from the BLRP than in soil from the unsown pasture. In this study, plant-available inorganic-N appeared as a strong limiting factor for the growth of the non-legume component. The BLRP seems to be currently environmentally sound, since the risk of N loss is practically non-existent. However, the potentially mineralisable organic N is increasing, which requires a further monitoring of the soil N dynamic as the pasture ages.Los pastos biodiversos ricos en leguminosas (PBRL) están siendo recomendados para la ganadería extensiva, ya que pueden mejorar la calidad de los pastos. Sin embargo, las implicaciones en el balance de nitrógeno (N) en suelo, debido a la fijación biológica de N, deben ser monitorizadas. Este estudio se estableció para evaluar la disponibilidad de N en suelo en PBRL en comparación con pastizales naturales. El ensayo consistió en el establecimiento de especies nitrófilas (nabo y centeno) en matas rodeadas por anillos de PVC. Durante un año se monitorizaron también los niveles de N mineral en suelo. El N potencialmente disponible se determinó mediante el cultivo de raigrás en macetas y mediante varios análisis químicos de laboratorio. En los PBRL los valores medios de N recuperado por el nabo y el centeno fueron 30,6 y 31,1 kg ha –1, respectivamente, no existiendo diferencias significativas con los valores registrados en los pastos naturales. Durante todo el año se registraron niveles bajos de N inorgánico en suelo. El N recuperado por el raigrás fue significativamente más elevado en los PBRL que en el pasto natural. Los resultados mostraron que el N fue un factor ecológico muy limitante para el crecimiento de las especies no leguminosas. Por otro lado, en los PBRL el riesgo de pérdida de N para el medio ambiente fue prácticamente nulo. Sin embargo, el N orgánico potencialmente mineralizable aumenta en el suelo, lo cual justificaría la necesidad de realizar nuevos análisis de dinámica del N en el suelo en un futuro

Olive response to potassium applications under different water regimes and cultivars

Although potassium (K) is a macronutrient few studies have evaluated the response of olive tree to K fertilization. In this work results of two field and two pot K fertilizer experiments are presented. One of the field trials was conducted in a commercial young olive grove. The second was conducted in a plantation purposely established for this study. In the two fieldand thefirst potexperiment,theK supply was the single variation factor. The second pot experiment was arranged as a factorial with two K rates, two water regimes and two cultivars (‘Arbequina’ and ‘Cobranc¸osa’). K supply did not increase olive tree growth or yield. Accumulated olive yield in the first field experiment, for instance, varied from 2.46 and 2.84 kg tree-1, respectively in K treated and untreated plants. K supply increased the shoot/root ratio (1.6–2.0 from the control to the most fertilized treatment) and the concentration of K in roots (2.9–11.2 g kg-1) to a greater extent than in leaves (7.0–11.9 g kg-1), suggesting that shoots are a priority sink for K and roots may store the nutrient as a reserve. Plant water status and chlorophyll a fluorescence were not significantly affected by K applications. Plants suffering from water stress yielded less phytomass (40.2–56.4 g pot-1, respectively in control and well-watered plants) and showed higher K concentrations in leaves (14.2–11.6 g kg-1) and lower in roots (4.9–6.8 g kg-1) which is probably due to the reduction of K uptake from the dry soil. ‘Cobranc¸osa’ appeared to be more tolerant to water stress than ‘Arbequina’. These experiments showed a poor response of olive tree to K fertilization. Considering that K is usually applied by farmers every year, it seems that further studies on K fertilizationin olive are needed in order to adjust K fertilizer rates to crop needs.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013). The work was also funded by the INTERACT Project—‘‘Integrative Research in Environment, Agro-Chains and Technology’’, No. NORTE- 01-0145-FEDER-000017, in its line of research entitled ISAC, co-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020). For authors integrated in the CITAB research centre, it was further financed by the FEDER/ COMPETE/POCI—Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145- FEDER-006958, and by National Funds of FCT–Portuguese Foundation for Science and Technology, under the Project UID/ AGR/04033/2013.info:eu-repo/semantics/publishedVersio

Olive tree response to applied phosphorus in field and pot experiments

Phosphorus (P) application in olive orchards is very common in the Mediterranean basin although experimental evidence of crop response to applied P is practically non-existent. In this work soil P and tree P nutritional status of the olive groves of NE Portugal were assessed from a population of 1808 soil and 2252 leaf samples. Plant response to applied P was evaluated from two field and two pot experiments carried out with the cultivar ‘Cobrançosa’. The analyses of soil and leaf samples of the olive orchards of the region indicate that P fertilizer recommendations should be based on leaf rather than on soil analyzes, since the latter seems to overestimate the need for P. The field and pot experiments hardly showed any positive response to P applications, which is a sign that the use of P fertilizer in olive can be substantially reduced. Nonetheless, in one pot experiment, P application significantly increased total dry matter yield during three consecutive years, in a strict association with higher tissue P concentrations and enhanced photosynthetic activity, as revealed by gas exchange and chlorophyll fluorescence traits. The experimental results also showed that the roots can uptake and store P when available in the soil, which may buffer the levels of P in the shoots. The acid phosphate activity can provide useful information but deserves caution in the interpretation of results since it depends not only on the availability of inorganic P in the soil, but also on the available organic substrate and pH.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013). The work was also funded by the INTERACT project – “Integrative Research in Environment, Agro-Chains and Technology”, no. NORTE-01-0145- FEDER-000017, in its line of research entitled ISAC, co-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020). For authors integrated in the CITAB research centre, it was further financed by the FEDER/COMPETE/POCI – Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145-FEDER- 006958, and by National Funds of FCT–Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013.info:eu-repo/semantics/publishedVersio

The effect of nitrogen applications on the growth of young olive trees and nitrogen efficiency

Two field trials (FieldExp1 and FieldExp2) and a pot experiment (PotExp) were c0onducted over a period of 3 years to assess olive tree response to nitrogen (N) applications and to estimate apparent N recovery. FieldExp1 was installed in a 3-year-old olive grove. FieldExp2 consisted of a plantation of young rooted plants. Two treatments were applied in both experiments: N application and a nonfertilized control. In PotExp, 4 N rates were used. In FieldExp1, olive yield significantly increased with applied N in only 1 of the 3 growing seasons. In FieldExp2, aboveground dry matter yield significantly increased with N application. In PotExp, total dry matter yield displayed a typical saturation curve in response to N rates. The poor response of olive yield to N application might be due to the reduced amount of N removed in the crop, and also to the negative interaction found between N application and water deficit. Apparent N recovery reached values varying from 13.1% in FieldExp2 to ~100% in PotExp. The results indicate that the olive response to N and N use efficiency seem to be influenced more by the agroecological conditions defining target yield and N loss, rather than by plant species.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Program PT2020 for financial support to CIMO (UID/AGR/00690/2013). The work was also funded by the INTERACT project “Integrative Research in Environment, Agro-Chains and Technology”, no. NORTE-01-0145- FEDER-000017, in its line of research entitled ISAC, cofinanced by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020).info:eu-repo/semantics/publishedVersio

Os fungos micorrízicos comerciais na agricultura do Interior Centro e Norte de Portugal

Os fungos micorrízicos estabelecem relações mutuamente benéficas com as plantas cultivadas. Estas fornecem produtos da fotossíntese aos fungos e recebem em troca água e nutrientes. A aplicação de fungos micorrízicos comerciais não garante, contudo, benefícios para as plantas. As plantas estabelecem estas associações com a microbiologia nativa do solo, pelo que a aplicação de microrganismos comerciais pode ser redundante. Nestes textos discute-se se os fungos comerciais podem ser ferramentas úteis ao incremento da sustentabilidade dos sistemas de produção.Grupo Operacional “Novas práticas em olivais de sequeiro: estratégias de mitigação e adaptação às alterações climáticas” (Iniciativa ID 278). Grupo Operacional “EGIS, estratégias para a gestão do solo e da água em espécies produtoras de frutos secos” (Iniciativa ID 91).info:eu-repo/semantics/publishedVersio

Liming and application of nitrogen, phosphorus, potassium, and boron on a young plantation of chestnut

European chestnut is the most important cash crop in the highlands of NE Portugal. However, limited data on cropping technique are available to help farmers make decisions. This work is motivated by the lack of data related to chestnut response to fertilizer application. It reports results from a field fertilization trial consisting of the application of a combination of lime (L), nitrogen (N), phosphorus (P), potassium (K), and boron (B), namely LNPKB, NPKB, –NPKB, N–PKB, NP–KB, and NPK–B. Seedlings of chestnut were planted in June 2013 and grown for four growing seasons. Plant height, trunk diameter, and pruning wood were assessed every year and used as indicators of tree crop growth. Elemental leaf analysis and other tools [SPAD-502 chlorophyll meter; Field Scout CM 1000 NDVI (normalized difference vegetation index) meter, and the OS-30p+ fluorometer] were used to assess plant nutritional stresses. In January 2017 soil samples were collected at three depths (0–5, 5–10, and 10–20 cm) to determine several soil fertility parameters. The nonapplication of K and B reduced the tree crop growth and pruning residues. Leaf analysis revealed leaf K and B concentrations respectively in the NP–KB and NPK–B treatments to be in the deficient range previously established for chestnut. SPAD readings and NDVI detected the reduced availability of N associated with the –NPKB treatment but not the reduced plant growth associated with NP–KB or NPK–B treatments. The dark adaptation protocols of FV/FM, FV/F0, and OJIP measurements performed with the OS-30p+ fluorometer failed to diagnose the nutrient stresses detected by leaf analysis or the reduction in plant growth.info:eu-repo/semantics/publishedVersio

Uso de aminoácidos no setor dos frutos secos

Os hidrolisados de proteína e diversos outros compostos azotados têm vindo a ter uma presença crescente na alimentação humana e nas rações para animais, bem como em produtos para a nutrição das plantas. As versões comerciais mais comuns destinadas à nutrição vegetal surgem como produtos ricos em aminoácidos livres e péptidos, e são sobretudo recomendados para aplicação foliar, embora alguns sejam também recomendados para fertirrega, hidroponia e peletização de sementes. A gama presente no mercado é extensa e de composição por vezes muito complexa, uma vez que os produtos comerciais contendo aminoácidos resultam frequentemente de misturas de hidrolisados de proteína com extratos de algas e micronutrientes. Destes produtos espera-se sobretudo um efeito “bioestimulante nas plantas”, com múltiplos benefícios potenciais para os processos fisiológicos, que possam conduzir a aumentos de produtividade e/ou qualidade dos produtos agrícolas.Integrado nas actividades do Grupo Operacional EGIS – Estratégias de Gestão Integrado do Solo e da Água em Espécies Produtoras de Frutos Secos (Iniciativa ID 91).info:eu-repo/semantics/publishedVersio

Estudos de fertilização em castanheiro com aplicação de calcário, azoto, fósforo, potássio ou boro

Este trabalho foi motivado pela falta de informação disponível sobre resposta do castanheiro à correção do pH e à aplicação de outros fertilizantes ao solo, numa fase em que, face aos bons preços a que se vende a castanha, os produtores têm estado muito predispostos a investir na técnica cultural. O trabalho reporta resultados de um ensaio em castanheiro que decorreu durante quatro anos, onde se ensaiaram seis modalidades de fertilização: aplicação de calcário mais azoto (N), fósforo (P), potássio (K) e boro (B) (CalNPKB); aplicação de N, P, KeB (NPKB); aplicação de P, Ke B (-NPKB); aplicação de N, K e B (N-PKB); aplicação de N, Pe B (NP-KB); e aplicação de N, Pe K (NPK-B). Os tratamentos fertilizantes foram aplicados à instalação das jovens plantas no ano de plantação e mantidos por quatro anos consecutivos, com exceção do calcário que só foi aplicado à instalação. Foi avaliada a resposta das plantas aos tratamentos fertilizantes através da medição da sua altura e do diâmetro do tronco e da lenha de poda produzida, bem como do estado nutricional das plantas avaliado a partir de análises elementares às folhas e com aparelhos portáteis. As plantas dos tratamentos NPK-B, NP-KB e -NPKB revelaram, respetivamente, teores de B, Ke N significativamente mais baixos que os restantes tratamentos. O tratamento N-PKB não revelou teores de P mais baixos que os restantes e o tratamento CalNPKB não revelou teores de cálcio ou magnésio superiores aos restantes. A altura das plantas e o diâmetro dos caules foram significativamente mais baixos nas modalidades NPKB e NP-KB. Os resultados dos aparelhos portáteis de medição da condição das plantas confirmaram que a falta de B e K foram os tratamentos que mais reduziram o estado nutricional das plantas nos respetivos elementos e maior influencia negativa exerceram no crescimento em altura e engrossamento das árvores. Recomenda-se que as futuras recomendações de fertilizaçâo para esta cultura tenha estes dois elementos em conta.info:eu-repo/semantics/publishedVersio