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The aim of this study was to evaluate the efficiency of the porous ceramic cup extractors, associated with ion meters, for the determination of nutrients availability for bell pepper and melon crops in substrate. Substrate solution was acquired using aqueous extract 1:1.5 (v/v) and also the porous ceramic cup extractor. Electrical conductivity (EC), pH and macronutrient contents were determined for the substrate solution through analytical method. The concentrations of NO3- and K+ in the solutions obtained with porous ceramic cup extractors, and the N and K contents in the diagnostic leaf for nutritional evaluation were also determined. The concentrations of NO3- and K+ using the porous ceramic cup extractors have strong correlation (r=0.96 and 0.92, respectively) with the ones obtained using the standard method, as well as a moderate correlation (r=0.65) and a strong one (r=0.71) with contents of N and K, respectively, in the melon diagnostic leaf; and a weak correlation (r=0.36 and 0.26, respectively) in the bell pepper diagnostic leaf. The use of porous ceramic cup extractors for obtaining the substrate solution and the determination of the N-NO3- and K+ contents by means of specific ion meters are a fast method of evaluating nutrients availability in soilless cultures. O objetivo deste trabalho foi avaliar a eficiência de extratores de cápsula porosa, associados a medidores de íons específicos, para determinar a disponibilidade de nutrientes em pimentão e melão cultivados em substrato. A solução de substrato foi obtida utilizando o extrator aquoso 1:1,5 (v/v) e o extrator de cápsula porosa. A condutividade elétrica (CE), o pH e a concentração dos macronutrientes na solução do substrato foram determinados por meio do método analítico. Além disso, foram determinadas as concentrações de NO3‑ e K+ nas soluções obtidas com os extratores de cápsula porosa, bem como as concentrações de N e K na folha diagnose do estado nutricional. As concentrações de NO3- e K+ obtidas por extratores de cápsula porosa apresentam forte correlação (r=0,96 e 0,92, respectivamente) com as obtidas pelo método padrão, bem como correlação moderada (r=0,65) e forte (r=0,71) com as concentrações de N e K, respectivamente, na folha diagnose do estado nutricional do melão e, correlação fraca (r=0,36 e 0,26, respectivamente) na folha diagnose do estado nutricional do pimentão. A utilização de extratores de cápsula porosa para a obtenção da solução do substrato e, a determinação das concentrações de N-NO3- e K+ por medidores de íons específicos, é um método rápido para avaliar a disponibilidade de nutrientes em cultivos sem solo. &nbsp

SUMMARYMuch of the watermelon (Citullus lanatus) cultivation in Brazil is conducted in sandy soil and topographic conditions that favour the erosion process. Therefore, conservation tillage methods are critical for the sustainability of the production chain of this vegetable crop. We studied different tillage methods and cover crops in watermelon cultivation in the area of the reform of degraded pasture. For this purpose, two tillage methods were established as experimental treatments: minimum tillage preparation with subsoiling only, and no tillage. As cover crops white lupine (Lupinus albus) and bristle oat (Avena strigosa) were seeded. As control, watermelon was cultivated with conventional tillage, without prior cultivation of cover crops. For the experimental design, randomised blocks in a factorial arrangement with four replications were used. After liming and phosphate fertilisation of the soil, cover crops were cultivated in soil with minimum tillage and no tillage to produce straw to be used for soil cover, where subsequently the watermelon was grown. The productivity of dry mass and nutrient accumulation in the shoot of cover crops, the soil properties and the watermelon agronomic performance were evaluated. White lupine had better performance in the production of dry mass and nutrient accumulation in shoot than bristle oat. There were differences among treatments for soil penetration resistance, where in conventional tillage the values were lower in the first 30 cm of depth in relation to no-tillage cultivation. The tillage method also affected the fertility of the soil at a depth of 0 to 20 cm. The no tillage provided increased nitrogen leaf content in watermelon regardless of cover crops but restricted root growth in relation to minimum tillage and conventional tillage. Watermelon had similar commercial production by different treatments, with reduction only in no tillage on bristle oat straw.

Made available in DSpace on 2018-11-26T17:32:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-05-19 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Predilecta Foods, Ltda. Natural Sciences and Engineering Research Council of Canada Over the past 20 years, the use of center-pivot irrigation has increased tomato (Solanum lycopersicum L.) yields in Brazil from 42 Mg ha(-1) to more than 80 Mg ha(-1). In the absence of field trials to support fertilizer recommendations, substantial amounts of phosphorus (P) have been applied to crops. Additional P dosing has been based on an equilibrated nutrient P budget adjusted for low-P fertilizer-use efficiency in high-P fixing tropical soils. To document nutrient requirements and prevent over-fertilization, tissue samples and crop yield data can be acquired through crop surveys and fertilizer trials. Nevertheless, most tissue diagnostic methods pose numerical difficulties that can be avoided by using the nutrient balance concept. The objectives of this study were to model the response of irrigated tomato crops to P fertilization in low- and high-P soils and to provide tissue diagnostic models for high crop yield. Three P trials, arranged in a randomized block design with six P treatments (0-437 kg P ha(-1)) and three or four replications, were established on a low-P soil in 2013 and high-P soils in 2013 and 2014, totaling 66 plots in all. Together with crop yield data, 65 tissue samples were collected from tomato farms. We found no significant yield response to P fertilization, despite large differences in soil-test P (coefficient of variation, 24%). High- and low-yield classes (cutoff: 91 Mg fruits ha(-1)) were classified by balance models with 78-81% accuracy using logit and Cate-Nelson partitioning models. The critical Mahalanobis distance for the partition was 5.31. Tomato yields were apparently not limited by P but were limited by calcium. There was no evidence that P fertilization should differ between center-pivot-irrigated and rain-fed crops. Use of the P budget method to arrive at the P requirement for tomato crops proved to be fallacious, as several nutrients should be rebalanced in Brazilian tomato cropping systems. Sao Paulo State Univ, Dept Plant Prod, Jaboticabal, Brazil Univ Laval, Dept Soils & Agrifood Engn, Quebec City, PQ, Canada Sao Paulo State Univ, Dept Agron, Registro, Brazil Univ Fed Ceara, Dept Plant Sci, Fortaleza, Ceara, Brazil Sao Paulo State Univ, Dept Plant Prod, Jaboticabal, Brazil Sao Paulo State Univ, Dept Agron, Registro, Brazil FAPESP: 2013/24447-4 FAPESP: 2013/24404-3 Natural Sciences and Engineering Research Council of Canada: NSERC-DG 2254

The influence of plant population (31,250 and 46,875 plants ha -1 ) and nitrogen doses (0, 100, 200, and 300 kg ha -1 ) on the accumulation of macronutrients by cabbage plants was studied in Jaboticabal, Brazil, from February 18 to June 2, 2004. The experimental design was a randomized complete block in a 2 × 4 factorial scheme, with three replications. Differences in the amount of macronutrients accumulated by cabbage as function of N dose and plant population, were observed. The largest amounts of macronutrients were detected at the end of the plant cycle when the plant population was the lowest. The amounts of N, P, K, and S were not significantly different when the N dose was increased from 100 to 300 kg ha -1 . The accumulated amounts of Ca and Mg were not significantly different when the N dose was increased from 200 to 300 kg ha -1 . The decreasing sequence of macronutrient extraction (Ca, N, K, Mg, P, and S) was not altered by the treatments. The period from 40 to 60 days after transplantation was responsible for half of the macronutrient accumulation by the cabbage plants. Con el fin de evaluar las interacciones entre las densidades de poblacion (31250 y 46875 plantas ha -1 ) y el nitrogeno (0, 100, 200 y 300 kg ha -1 ) en la acumulacion de macronutrientes en la col cv. 'Astrus', se realizo un experimento en Jaboticabal (Brasil) del 18 de febrero al 2 de junio de 2004. El diseno experimental fue de bloques al azar factorial 2 × 4 con tres repeticiones. Se observo diferencia en la cantidad de macronutrientes de la col en funcion de N y la densidad de poblacion. Se observaron las mayores cantidades al final del ciclo con la menor densidad de la siembra, pero las cantidades de N, P, K y S no fueron diferentes cuando se utilizan de 100 a 300 kg ha -1 de N. Para Ca y Mg, las cantidades no fueron diferentes cuando se fertilizo con 200 o 300 kg ha -1 de N. La secuencia descendente de extraccion de macronutrientes (Ca, N, K, Mg, P y S) no se vio afectada por los tratamientos. El periodo de 40 a 60 dias despues del trasplante fue responsable de la mitad de las cantidades acumuladas de macronutrientes en planta de la col.