Critérios para o manejo da adubação nitrogenada na cultura do feijão utilizando clorofilômetro portátil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Desempenho agronômico e diagnose foliar da aveia preta em função da calagem em plantio direto

The soil acidity in no tillage system could be resolved by lime superficial application, improvement to crop mineral nutrition and yield. The experiment carried out on a Rhodic Kandiudalf in Botucatu, São Paulo State, Brazil, in dry conditions, aiming to evaluate the agronomic development and leaf diagnosis of black oat plants, under superficial liming in no tillage system. A randomized complete block design was used, with four replications, the treatments were superficial application of different dolomítico lime rates (R0 = zero – without lime; R1 = 1,8 t ha-1 – lime to increase the base saturation at 50%; R2 = 3,6 t ha-1 – lime to increase the base saturation at 70% and R3 = 5,4 t ha-1 – lime to increase the base saturation at 90%), in October 2002. The black oat Common cultivar was seed in April 2004, in to second year, after the crop rotation of millet (spring) – common bean (summer) – black oat (autumn-winter). The results showed that: the black oat had yield increase by superficial liming, mainly to most dry matter and grain per panicule. Beyond, the superficial liming application did not prejudice leaf diagnosis of culture.

Compositional nutrient diagnosis of corn using the Mahalanobis distance as nutrient imbalance index

Parent, L. E., Natale, W. and Ziadi, N. 2009. Compositional nutrient diagnosis of corn using the Mahalanobis distance as nutrient imbalance index. Can. J. Soil Sci. 89: 383-390. Compositional nutrient diagnosis (CND) provides a plant nutrient imbalance index (CND - r(2)) with assumed chi(2) distribution. The Mahalanobis distance D(2), which detects outliers in compositional data sets, also has a chi(2) distribution. The objective of this paper was to compare D(2) and CND - r(2) nutrient imbalance indexes in corn (Zea mays L.). We measured grain yield as well as N, P, K, Ca, Mg, Cu, Fe, Mn, and Zn concentrations in the ear leaf at silk stage for 210 calibration sites in the St. Lawrence Lowlands [2300-2700 corn thermal units (CTU)] as well as 30 phosphorus (2300-2700 CTU; 10 sites) and 10 nitrogen (1900-2100 CTU; one site) replicated fertilizer treatments for validation. We derived CND norms as mean, standard deviation, and the inverse covariance matrix of centred log ratios (clr) for high yielding specimens (>= 9.0 Mg grain ha(-1) at 150 g H(2)O kg(-1) moisture content) in the 2300-2700 CTU zone. Using chi(2) = 17 (P < 0.05) with nine degrees of freedom (i.e., nine nutrients) as a rejection criterion for outliers and a yield threshold of 8.6 Mg ha(-1) after Cate-Nelson partitioning between low- and high-yielders in the P validation data set, D(2) misclassified two specimens compared with nine for CND -r(2). The D(2) classification was not significantly different from a chi(2) classification (P > 0.05), but the CND - r(2) classification differed significantly from chi(2) or D(2) (P < 0.001). A threshold value for nutrient imbalance could thus be derived probabilistically for conducting D(2) diagnosis, while the CND - r(2) nutrient imbalance threshold must be calibrated using fertilizer trials. In the proposed CND - D(2) procedure, D(2) is first computed to classify the specimen as possible outlier. Thereafter, nutrient indices are ranked in their order of limitation. The D(2) norms appeared less effective in the 1900-2100 CTU zone.

Establishing Standards for the Integrated Recommendation and Diagnosis System (DRIS) for Irrigated Bean Crops

This article addresses the establishment of integrated diagnostics and recommendation system (DRIS) standards for irrigated bean crops (Phaseolus vulgaris) and compares leaf concentrations and productivity in low- and high-productivity populations. The work was carried out in Santa Fe de Goias, Goias State, Brazil, in the agricultural years 1999/2000 and 2000/2001. For the nutritional diagnosis, leaf samples were collected, and leaf concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) were established in 100 commercial bean crops. A database was set up listing the leaf nutrient content and the respective productivities, subdivided into two subpopulations, high and low productivity, using a bean yield value of 3000 kg ha-1 to separate these subpopulations. Sufficiency values found in the high-productivity population matched only for the micronutrients B and Zn. The nutritional balance among the populations studied was coherent and was lower in the high-productivity population. The DRIS standards proposed for irrigated bean farming were efficient in evaluating the nutritional status of the crop areas studied. Calcium, Cu, and S were found to be the least available nutrients, indicating high response potential for the fertilizing using these nutrients.

The CND-Goiaba 1.0 software for nutritional diagnosis of guava (Psidium guajava L.) 'Paluma', in Brazil

Computer programs enable the transformation of raw data into useful information for decision making in many fields, including agriculture. Various programs have been developed to assist farmers to make better decisions about crop management practices and plant nutrition parameters. This article introduces the CND-Goiaba 1.0 software (C Sharp) and its use as a tool to perform the mathematical calculations involved in determining the compositional nutrient diagnosis (CND) indexes for the guava tree. This program was developed in Brazil, the world's leading producer of red guavas. A database was created based on 205 leaf samples collected in commercial plots (sampling units) of cultivated 'Paluma' guava trees (Psidium guajava L.) with ages between 5 and 20 years, during the 2009-2010 and 2010-2011 growing seasons. The production data were normally distributed according to the Shapiro-Wilk test (W=0.988; p=0.11). The software made it possible to diagnose that 63% of the orchards evaluated needed to improve the nutritional status of their trees. The CND method showed severe nutritional imbalances in Mg and Zn in these orchards. © ISHS.

High-throughput sugarcane leaf analysis using a low cost closed-vessel conductively heated digestion system and inductively coupled plasma optical emission spectroscopy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dris norms and critical leaf nutrient levels for ‘Niagara rosada’ grape in Jundiaí region, São Paulo (Brasil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)