O eucalipto é a essência florestal mais plantada no Brasil (em torno de 3,5 milhões ha), correspondendo à aproximadamente 70 % da área total de plantios florestais. Em ambientes tropicais, a sustentabilidade da produção florestal é governada, principalmente, pelos fluxos de água e nutrientes do solo, uma vez que, geralmente, temperatura e radiação solar não são limitantes. A limitação nutricional é freqüentemente corrigida pelo adequado manejo nutricional. O recurso água tem sido considerado como mais limitante à produtividade florestal nos trópicos. A avaliação e a compreensão de como os recursos água e nutrientes regulam a produtividade florestal é fundamental para a predição do potencial produtivo do povoamento florestal e para subsidiar aplicação das técnicas de manejo mais adequadas ao crescimento florestal. Assim, objetivou-se neste trabalho avaliar o crescimento e partição de biomassa e nutrientes; bem como as propriedades intensivas da parte aérea (folhas) e do sistema radicular (raízes finas) e a eficiência de uso dos recursos água e nutrientes minerais em função da aplicação de água, via irrigação e água mais nutrientes, via fertirrigação. Para tanto, em outubro de 2001, na região do Vale do Rio Doce -MG, foi instalado experimento composto por quatro materiais genéticos clonais de eucalipto: 57 e 2719 -? Híbridos de Eucalyptus grandis, Rio Claro; 129 &#8211; Eucalyptus grandis e 1215 - E. urophylla x E. Grandis, &#8220;Urograndis&#8221;, e três tratamentos de água e nutrientes aplicados ao solo (irrigado, fertirrigado e controle). Todas as árvores de cada parcela experimental tiveram seus diâmetro a 1,3 m de altura (dap) e altura total (Ht) monitorados por inventários florestais realizados a cada três meses a partir dos 13 meses de idade, o que possibilitou ajustar equações de regressão para cada material genético descrevendo o comportamento do dap, Ht, área basal (B) e volume de tronco (Vt) em função da idade dos plantios. Para cada parcela experimental, foram abatidas cinco árvores, escolhidas dentro de uma faixa crescente de dap. Todas as árvores abatidas tiveram seus troncos submetidos à cubagem rigorosa e seus compartimentos (folha, galho, casca e lenho) foram separados e pesados, sendo retiradas amostras para a determinação do peso seco, teor e conteúdo de nutrientes; foi retirada uma amostra adicional de folhas para a determinação da área foliar específica e índice de área foliar. Amostras de raízes finas (< 2 mm) foram retiradas de cada árvore abatida, sendo lavadas, pesadas e escaneadas, determinando-se então seu peso seco, a superfície radicular específica e índice de área radicular. A fertirrigação proporcionou maior crescimento em volume e biomassa de tronco, e a irrigação pouco afetou o crescimento da floresta. A fertirrigação também levou a maiores conteúdos de nutrientes minerais na parte área e tronco sendo a magnitude distinta de acordo com o material genético. A fertirrigação promoveu maior índice de área foliar, área radicular específica e índice de área radicular, mas pouco influenciou a área foliar específica, a qual foi mais influenciada pela classe de produtividade, tendo seu valor reduzido com o aumento do grau de dominância da árvore. Em média, a fertirrigação elevou a eficiência de uso de nutrientes para a produção de biomassa de parte aérea, tronco, folhas e raiz finas; contrariamente, a aplicação conjunta de água e nutrientes, via fertirrigação reduziu a eficiência de uso de água para a produção de biomassa de tronco. Assim conclui-se que a disponibilização de água e nutrientes altera o comportamento de crescimento e partição de biomassa e nutrientes, bem como suas eficiências de uso e as propriedades intensivas das superfícies de aquisição de recursos (folhas e raízes finas), em magnitudes distintas com o material genético. | Eucalypt is the main forest essence planted in Brazil (approximately 3.5 million ha) and represents roughly 70 % of the total forestry planting. In tropical environments, the sustainability of the forest production is primarily dictated by water and nutrient fluxes in the soil, provided temperature and solar radiation are not limiting. Nutrient limitation has often been corrected through adequate nutritional management, thus being of secondary importance for most commercial Eucalypt plantations. Water has otherwise been considered as the most limiting resource to eucalypt productivity in the tropics. The evaluation and the comprehension of how water and nutrients regulate forestry productivity are key to predict the productive potential of the forest stand and to subsidize the utilization of management practices more adequately to forestry growth. Being said this, the main objectives of the present work were to evaluated the forest growth, the biomass and nutrient partitioning, the intensive properties of leaves and fine roots and the use efficiency of water and nutrients as a function of irrigation (water) and fertirrigation (water + nutrients) treatments. The experiment was set in October 2001 in the Rio Doce River Valley, Central-Western region of Minas Gerais State, Brazil. The experiment was compounded by four clonal genetic material of eucalypt: 57 and 2719 - Rio Claro and Eucalyptus grandis hybrids; 129 - Eucalyptus grandis hybrids and 1215 - Eucalyptus urophylla x Eucalyptus grandis, "Urograndis", and three different treatments of water and nutrients (irrigation, fertirrigation and control). All trees in the experimental plot had their diameter at breast height (dbh) and total height (Ht) monitored by forest inventory, which were made every three months starting when the trees were 13 months old. With this data it was possible to fit regression equations for each eucalypt genetic material describing the behavior of dbh, Ht, basal area (B) and trunk volume (Vt) as a function of the stand age. Five trees per experimental plot representing the range in tree sizes were felled at ground level and separated into foliage, branches, stemwood and bark components. Total fresh weights were determined in the field and all tissues were subsampled for moisture, nutrient contents and dry weight determination. All trunks had their volume determined by rigorous scaling. Additional subsamples of fresh foliage were collected from each sampled tree and specific leaf area (SLA) was determined. Leaf area index (LAI) was determined using the data from SLA and total foliage biomass of each sampled tree. Fine roots (< 2 mm) were collected from each sampled tree, then, washed, scanned and dried until constant weight being achieved. Additionally, root specific area and root area index were also obtained from the plant material. The fertirrigation had positive effects on trunk growth, volume and biomass. Conversely, irrigation had no affect on stand growth. Fertirrigation also increased the nutrients content in the above ground biomass with different magnitude with regards to the genetic material besides providing a greater leaf area index, root specific area and root area index, but it had little influence on leaf specific area, which was more influenced by the productive class where it had its value reduced when the degree of dominance of the tree went up. On average, fertirrigation increased the nutrients use efficiency for production of total above ground biomass, trunk biomass, foliage biomass and fine roots biomass, but it decreased water use efficiency for production of trunk biomass. Thus, it is concluded that water and nutrient availability change the behavior of the stand growth, nutrient and biomass partitioning as well as the studied resources use efficiency and intensive properties of the resource acquisition (leaves and fine roots), with different magnitude according with the genetic material. | Conselho Nacional de Desenvolvimento Científico e Tecnológico

In Irapuato, Guanajuato, Mexico, strawberry crops represent an important source of jobs for many people, particularly women. Traditionally, the crop is fertilized with high a rate of N (350-500 kg N ha(-1)). Thus, the objectives in this study were 1) to quantify the nitrogen uptake derived from fertilizer by the crop through the 15N isotopic technique, and 2) to quantity the water productivity. A strawberry crop cv. Chandler was transplanted to the field and fertilized with 300 kg N ha(-1) as ammonium sulphate 1% 15N atoms excess. The fertilization was split in three applications of 100 kg N ha(-1) at 30, 91 and 157 days after transplanting (dat). The lowest N-efficiency occurred in the period 0-64 dat (7%). The berries always showed the lowest N-efficiency (< 1%). The N-efficiency occurred in stage 64-91 dat. The highest N uptake from fertilizer occurred during the periods 64-91, 128-157, and 188-219 dat. In relation to water, the results indicate "poor" water productivity. The highest value observed occurred between 157-188 dat and is directly related to peak biomass accumulation. The calculated value of water productivity is 1.6 m3 kg(-1) fruit. Our data illustrate the need to continue with studies focused on the optimization the N-fertilizer and water.

The effect of three irrigation calendars: 0-46, 0-40-70, and 0-40-70-90 days after sowing (das) and three N fertilization rates: 120, 180, and 240 kg ha(-1) applied at sowing were studied using 15N and neutron probe on barley (Hordeum vulgare L.). A split plot design with four replicates was used. The results showed that the efficiency use of N-fertilizer in the different irrigation calendars under study was similar (< 22%). The highest proportion of nitrogen derived from fertilizer was low (< 40%) and occurred between 52 to 66 das. Interestingly, eliminating irrigation during flowering stage resulted in an increase in N absorption from fertilizer. In conclusion, a management of these inputs, two irrigation periods and 180 kg N ha(-1) resulted in better management in barley production system.

Background: Crop production in the arid and semi-arid lands (ASALs) is constrained by erratic rainfall and poor soil fertility. Therefore, climate smart agriculture mechanisms such as in-situ rainwater harvesting technologies and recommended fertilizer rates would be vital for ensuring food security. Objective: To evaluate selected in-situ water harvesting technologies and fertilizer rates on soil water content and yield of maize and beans at KALRO Katumani Research Center in Machakos County, Kenya during the 2019 and 2020 short and long rain seasons, respectively. Methodology: The experiment was established in a randomized complete block design with a split-split plot arrangement, replicated three times, with in-situ water harvesting technologies comprising of zai pits, ngolo pits, contour furrows and conventional tillage, as the main plots, whereas the split plots were varying rates of fertilizer inputs: Di-ammonium phosphate (DAP), goat manure and control. The split-split plots comprised of maize and beans cropping systems. Soil moisture content was assessed at 4, 8, 12 and 16 weeks after emergence, whilst nutrient uptake, use efficiency and crop yields at physiological maturity. Data was subjected to analysis of variance. Results: Soil moisture, maize and beans yields, nutrient uptake and use efficiency were significantly (p ≤ 0.05) increased by in-situ water harvesting technologies and fertilizer inputs. Highest soil moisture content was recorded under zai and ngolo pits and lowest in conventional tillage treatments. Ngolo pits recorded higher maize and beans grain yield. Application of DAP fertilizer increased maize and beans grain yield compared to control. Intercropping maize and beans increased grain yield significantly (p ≤ 0.05) compared to sole maize and sole beans. Implications. There is need for promoting a combination of in-situ rainwater harvesting technologies especially ngolo and zai pits with application of DAP+ manure in semi-arid areas where water is scarce coupled with poor soil fertility. Conclusion: Ngolo and zai pits increased soil water retention capacity while application of DAP fertilizer led to increased crop yield and the study therefore recommends their adoption within the study area and extrapolation to areas of similar conditions. | Antecedentes: La producción de cultivos en las tierras áridas y semiáridas (ASAL) se ve limitada por la irregularidad de las lluvias y la escasa fertilidad del suelo. Por lo tanto, los mecanismos de agricultura climáticamente inteligente, como las tecnologías de recolección de agua de lluvia in situ y las tasas de fertilizante recomendadas, serían vitales para garantizar la seguridad alimentaria. Objetivo: Evaluar tecnologías seleccionadas de recolección de agua in situ y tasas de fertilizantes sobre el contenido de agua del suelo y el rendimiento de maíz y frijoles en el Centro de Investigación KALRO Katumani en el condado de Machakos, Kenia, durante las temporadas de lluvia corta y larga de 2019 y 2020, respectivamente. Metodología: El experimento se estableció en un diseño de bloques completos al azar con un arreglo de parcelas divididas y divididas, replicado tres veces, con tecnologías de recolección de agua in situ que comprenden pozos zai, pozos ngolo, surcos de contorno y labranza convencional, como las parcelas principales. mientras que en las parcelas divididas se variaron las tasas de aportes de fertilizantes: Fosfato diamónico (FDA), estiércol caprino y testigo. Las parcelas divididas fueron constituidas por los sistemas de cultivo de maíz y frijol. El contenido de humedad del suelo se evaluó a las 4, 8, 12 y 16 semanas después de la emergencia, mientras que la absorción de nutrientes, la eficiencia de uso y el rendimiento de los cultivos en la madurez fisiológica. Los datos se sometieron a análisis de varianza. Resultados: La humedad del suelo, los rendimientos de maíz y frijol, la absorción de nutrientes y la eficiencia del uso aumentaron significativamente (p ≤ 0.05) con las tecnologías de recolección de agua in situ y los aportes de fertilizantes. El contenido de humedad del suelo más alto se registró en pozos zai y ngolo y el más bajo en tratamientos de labranza convencional. Los pozos de ngolo registraron un mayor rendimiento de grano de maíz y frijol. La aplicación de fertilizante DAP aumentó el rendimiento de grano de maíz y frijol en comparación con el control. El cultivo intercalado de maíz y frijol incrementó el rendimiento de grano (p ≤ 0.05) en comparación con el maíz único y el frijol único. Implicaciones. Es necesario promover una combinación de tecnologías de recolección de agua de lluvia in situ, especialmente pozos ngolo y zai con la aplicación de estiércol DAP+ en áreas semiáridas donde el agua escasea y la fertilidad del suelo es deficiente. Conclusión: Los pozos ngolo y zai aumentaron la capacidad de retención de agua del suelo, mientras que la aplicación de fertilizante DAP condujo a un aumento del rendimiento de los cultivos y, por lo tanto, el estudio recomienda su adopción dentro del área de estudio y la extrapolación a áreas de condiciones similares.