The premises underlying univariate (CVA = critical value approach) and bivariate (DRIS = diagnosis and recommendation integrated system) diagnostic systems were reexamined with regard to compositional data analysis (CDA). CDA recognizes a structure of dependence among plant nutrients, the bounded sum constraint to one (the whole composition equals 100% or 1), and removes the curvature problem carried by crude components and by dual ratios or logratios when treated in isolation. Linearization by “rowcentered logrationing” of nutrient fractions shows great potential for carrying multivariate diagnosis and principal component analysis on nutrient data. Compositional nutrient diagnosis (CND) is supported by the theory of CDA. CND is the multivariate expansion of CVA and DRIS and is fully compatible with PCA. CND takes all possible nutrient interactions into account. CND nutrient indices are composed of two separate functions, one considering differences between nutrient levels, another examining differences between nutrient balances (as defined by nutrient geometric means), of individual and target specimens. These functions indicate that nutrient insufficiency can be corrected by either adding a single nutrient or taking advantage of multiple nutrient interactions to improve nutrient balance as a whole. A theoretical interpretative table is presented for CND.

Tissue analysis is commonly used in ecology and agronomy to portray plant nutrient signatures. Nutrient concentration data, or ionomes, belong to the compositional data class, i.e., multivariate data that are proportions of some whole, hence carrying important numerical properties. Statistics computed across raw or ordinary log-transformed nutrient data are intrinsically biased, hence possibly leading to wrong inferences. Our objective was to present a sound and robust approach based on a novel nutrient balance concept to classify plant ionomes. We analyzed leaf N, P, K, Ca, and Mg of two wild and six domesticated fruit species from Canada, Brazil, and New Zealand sampled during reproductive stages. Nutrient concentrations were (1) analyzed without transformation, (2) ordinary log-transformed as commonly but incorrectly applied in practice, (3) additive log-ratio (alr) transformed as surrogate to stoichiometric rules, and (4) converted to isometric log-ratios (ilr) arranged as sound nutrient balance variables. Raw concentration and ordinary log transformation both led to biased multivariate analysis due to redundancy between interacting nutrients. The alr- and ilr-transformed data provided unbiased discriminant analyses of plant ionomes, where wild and domesticated species formed distinct groups and the ionomes of species and cultivars were differentiated without numerical bias. The ilr nutrient balance concept is preferable to alr, because the ilr technique projects the most important interactions between nutrients into a convenient Euclidean space. This novel numerical approach allows rectifying historical biases and supervising phenotypic plasticity in plant nutrition studies.

Changes in phosphorus fractions of a humic gleysol as influenced by cropping systems and nutrient sources. Can. J. Soil Sci. 81: [175][176][177][178][179][180][181][182][183]. Information about the dynamics of soil P fractions is useful to predict their bioavailability and risk of P transfer from soils to surface waters. The objective of this study was to assess the effects of cropping systems and nutrient sources on P fractions in a Labarre silty clay (Humic Gleysol). Soil samples (0-15 cm) were collected in 1989, 1994 and 1997 from a field with four cropping systems, combining two crop rotations, barley (Hordeum vulgare L.) monoculture and 3-yr barley-forage rotation, with two tillage operations (chisel and moldboard plowing) as main plots, and two nutrient sources (mineral fertilizer and liquid dairy manure) as subplots. A modified Hedley sequential fractionation scheme was used. The inorganic P (P i ) fractions (resin-P, NaHCO 3 -P i , and NaOH-P i ) increase with time in all cropping system and nutrient source combinations. Organic (P o ) fraction (NaHCO 3 -P o and NaOH-P o ) changes were related to C inputs and total soil C contents. The barley monoculture combined with mineral fertilizer slightly reduced NaHCO 3 -P o and NaOH-P o . The barley-forage rotation increased labile P o fractions. Rotation, chisel plowing and liquid dairy manure addition result in a buildup of labile P. A larger labile P increment per unit of P added, in surplus to plant exports, was observed with dairy manure than for mineral fertilizer, suggesting a higher risk of surface water contamination by P. Cropping systems and nutrient sources have a large influence on the changes in P fractions in this fine-textured Gleysolic soil. Les fractions du P inorganique (P i ) (P-résine, P i -NaHCO 3 et P i -NaOH) ont cru avec le temps dans toutes les combinaisons de sytèmes culturaux et sources d'éléments nutritifs. Les changements des fractions du P organique (P o, P o -NaHCO 3 et P o -NaOH ) étaient reliés aux apports de C et à la teneur en C total du sol. La monoculture combinée aux fertilisants minéraux a légèrement réduit les P o -NaHCO 3 et P o -NaOH. La rotation, le chisel et le lisier ont accru le P labile. Une augmentation plus marquée du P labile par unité de P ajouté en surplus des exportations végétales est observée avec le lisier qu'avec les fertilisants minéraux, suggérant un risque plus élevé de contamination des eaux de surface par le P. Les systèmes culturaux et les sources d'éléments nutritifs ont un impact marqué sur l'évolution des formes de P dans ce gleysol à texture fine. Mots clés:Fractions du P, rotations culturales, lisier de bovins laitiers, charrue chisel, charrue à versoir Crop rotation has major effects on soil organic matter dynamics and this can directly or indirectly affect the soil nutrient status (Campbell et al. 1990). A series of studies has assessed the impact of cropping intensity on the changes in P forms in soils (Wagar et al. 1986; McKenzie et al. 1992a,b;Bowman and Halvorson 1997). These studies ind...

Khiari, L. and Parent, L. E. 2005. Phosphorus transformations in acid light-textured soils treated with dry swine manure. Can. J. Soil Sci. 85: 75-87. Organic matter can sorb P in acid soils through metal-organic matter-phosphate complexes. The pyrophosphate extractable Al and Fe and soil C contents were hypothetized to influence P partitioning in Ferro-Humic Podzols. Reaction of added P may be mitigated by adding lime or organic matter as dry swine manure (DSM) together with mineral P fertilizers. Three soils had 40 to 50 g kg -1 of soil organic matter (SOM) content, and 76 to 140 mmol (Al + Fe) pyro kg -1 . A peaty soil phase had 200 g SOM kg -1 , and 58 mmol (Al + Fe) pyro kg -1 . Rates of monoammonium phosphate were 0, 27, 69, and 144 kg P ha -1 in a simulated fertilizer band. Rates of DSM and lime were 800 and 185-369 mg per 35 mL of soil, respectively. After 6 wk of incubation, soil P was fractionated sequentially into aluminium bound P (Al-P), iron bound P (Fe-P), and loosely bound P. Total P, desorbed P and organic P were determined in separate subsamples. A proportion of 79-92% of added P was recovered as Al-P and Fe-P in the three low SOM soils, compared to 51-61% in the high SOM soil. The DSM increased loosely bound P from 25 to 34% in the high SOM soil and from 4.8 to 5.9% in low SOM soils. With DSM, the proportion of desorbed P was much higher in the high (70%) than in low SOM (22%) soils. Compared to the non-amended treatment, lime showed no significant effect on any P fraction but desorbed P. The DSM increased P availability in the fertilizer band considerably more in the soil having the lowest (Al + Fe) pyro /C ratio. Après 6 semaines d'incubation, le P fut fractionné de façon séquentielle en Al-P, Fe-P et P faiblement lié. Le P total, le P désorbé et le P organique furent analysés dans des échantillons séparés. Entre 79 et 92% du P ajouté aux sols faibles en MO (FMO) fut récupéré sous forme d'Al-P et de Fe-P, comparativement à 51-61% pour le sol haut en MO (HMO). En présence de FPD, la proportion de P extrait à l'eau (P désorbé) fut plus élevée dans le sol HMO (70%) que dans les sols FMO (22%). Par rapport au témoin non amendé, la chaux n'a eu aucun effet significatif sur les fractions du P sauf sur le P désorbé. Le FPD a augmenté la disponibilité du P dans la bande d'engrais, et de façon la plus importante dans le sol à rapport (Al + Fe) pyro sur C le plus faible.

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.

RESUMO -A produtividade agrícola nos trópicos é afetada, principalmente, pelos fatores ligados à acidez do solo (pH, saturação por bases, acidez potencial, disponibilidade de nutrientes). A calagem é uma prática bem conhecida para corrigir a acidez do solo em culturas anuais, ainda que não seja praticada com a regularidade necessária. Entretanto, em culturas perenes, a incorporação de corretivos é mais complexa, devido às características desse grupo de plantas e à carência de informações científicas sobre o assunto. Em condições de acidez, a calagem promove a neutralização do Al 3+ , a elevação do pH e o fornecimento de Ca e Mg, possibilitando a proliferação de raízes, com reflexos positivos no crescimento da parte aérea das plantas. Contudo, devido à baixa solubilidade e à lenta movimentação do calcário ao longo do perfil do solo, há obrigatoriedade de se fazer distribuição uniforme e incorporação profunda, antecedendo a implantação do pomar, a fim de garantir o eficiente aproveitamento de água e de nutrientes contidos nessas camadas. A calagem deve ser considerada um investimento, pois seus benefícios perduram além de um ano ou de uma safra agrícola. Isso se deve ao efeito residual dos corretivos de acidez do solo, sendo o tempo de duração desse efeito dependente de vários fatores, entre os quais: condições edafoclimáticas, cultura, manejo da área e tipo de corretivo empregado. Em geral, partículas maiores de calcário têm efeito residual mais prolongado, sendo empregadas na implantação dos pomares. No entanto, a relação entre o tamanho da partícula e o efeito residual tem sido pouco pesquisada, devido à necessidade de estudos de longa duração. Em função das elevadas doses de adubos nitrogenados utilizadas nos pomares de altos rendimentos, a acidez do solo aumenta, como resultado do processo de nitrificação. Em pomares já implantados, o procedimento atualmente utilizado pelos produtores é a incorporação superficial do calcário na área. As recomendações talvez fossem outras, caso houvesse maior subsídio da pesquisa, tendo em vista os diversos problemas fitossanitários que podem ocorrer, direta ou indiretamente da prática da incorporação do corretivo, tais como redução do sistema radicular, ferimento das raízes e consequente risco de infecções, com disseminação de pragas e doenças no pomar. O objetivo desta revisão é apresentar os principais resultados de pesquisas sobre o assunto, mostrando os efeitos da calagem sobre a fertilidade do solo, a nutrição e a produtividade de frutíferas de grande importância econômica para o Brasil, bem como discutir a duração do efeito residual dos corretivos e a dose mais ecônomica a ser aplicada nos pomares de frutas em implantação e em produção. Termos para Indexação: Corretivo de acidez, Calcário, Implantação de pomar. SOIL ACIDITY AND LIMING IN TROPICAL FRUIT ORCHARDSABSTRACT -Agricultural productivity in the tropics is affected first by soil acidity and related factors (pH, base saturation, potential acidity, nutrient availability). Liming is a well-known but irregularly used...

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The knowledge of P transformations is essential to understand the P behaviour in soils. Organic (Po) and inorganic (Pi) P fractions were obtained from the 0‐ to 30‐ and 30‐ to 90‐cm layers of a Labarre silty clay (fine, mixed, frigid, Humic Cryaquept) by a sequential extraction. Barley (Hordeum vulgare L.) monoculture and 3‐yr barley‐forage rotation as main plots, and two nutrient sources (mineral fertilizer and liquid dairy manure) as subplots were studied. Path analysis was used to describe soil P transformations between the falls of 1989 and 1997. Nutrient source was the main factor affecting P transformations in the 0‐ to 30‐cm soil layer, whereas crop rotation predominated in the subsoil. Pathways differed more for Po than for Pi pools. In the 0‐ to 30‐cm soil layer, 86 to 97% of the variation in resin‐P was the direct effect of added Pi The NaHCO3‐Pi and Po were sensitive to crop rotations and nutrient sources, and were transitory pools of soil P. The NaOH‐Pi was a sink for added Pi and a source of NaHCO3‐Pi Labile Pi tended to store as NaOH‐Po, which was the sink for added Po and immobilized soil Pi in the mineral fertilizer systems. Conversely, the NaOH‐Po was mineralized and contributed to labile Pi in dairy manure systems. The NaOH‐Po acted as store of subsoil Po in the monoculture but was the main source of labile P in the rotation systems. The P transformations in this Cryaquept were strongly influenced by nutrient sources and crop rotations.