Soil Chemical Analysis

Mineral Nutrition of Higher Plants, 2nd edition, H. Marschner. Academic Press, London (1995), 889, (ISBN 0-12-473543-6). Price: 29.95 Pound Sterling

A B S T R A C T Soil compaction influences all stages of crop growth, but in many low yield sugarcane fields critical levels and effects of soil compaction are ignored. Therefore, identifying localization and intensity of compaction are very relevant for descompactation of soil. In this context, this study aimed to apply three criteria for delineating zones for soil compaction management: soil layer where first appear values of soil penetration resistance considered critical for sugarcane growth; cone index for 0-40 cm layer, and depth of occurrence of maximum soil penetration resistance. Sampling was carried out in a grid with 113 points spaced at 100 m, georeferenced by means of a Global Positioning System receiver. Soil penetration resistance in eight layers of 5 cm depth, cone index and depth of occurrence of maximum penetration resistance were determined from data gathered by an automatic measuring penetrometer. Estimative of non-sampled values were obtained by means of kriging interpolation, which allowed drawing of contour maps and the definition of four regions in the field for site specific subsoiling . Palavras-chave: Saccharum ssp. resistencia do solo a penetracao geoestatistica penetrometro

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Revista Brasileira de Engenharia Agrícola e Ambiental

IN September 1920 there was a scare about the heavy mortality amongst the oysters on the layings of the Thames Estuary. This scare passed to Colchester, and to every part of the East Coast, and similar death-rates were also mentioned from the south and west. The matter was investigated by the Development Commission's Advisory Committee on Fishery Research, but so far as we can see from the Report before us, no accurate estimations were made of the deaths, either beforehand, or afterwards when it certainly would not have been too late; the Table given shows that unusual mortality was reported in the summer of 1921 in the Thames Estuary, and the only possible excuses for the lack of accurate investigation then are either that reports were not sent in at the time, or that the Development Commission refused to provide the funds for such. Oyster planters estimated the deaths in 1920 at 10 to 60 per cent, against an average of 10 to 15 per cent., but there is no indication upon what these estimates were based. As Holt in Ireland records, losses from all causes of 39-6 and 54-6 per cent, on accurate figures, and Bulstrode showed that an English planter laid 241 millions in 13 years, and only picked up and sold 105 millions, we may be allowed to doubt the accuracy of the belief in this greatly increased and “abnormal “mortality, especially as no information is supplied as to deaths and the working of the layings in 1918 and 1919. Ministry of Agriculture and Fisheries. Fishery Investigations. Series 2, Vol. 6, No. 3, 1923. An Account of Investigations into the Cause or Causes of the unusual Mortality among Oysters in English Oyster Beds during 1920 and 1921. Part 1.: Report. By Dr. J. H. Orton. (assisted in Laboratory Work by Miss Edith Worsnop. Pp. 199 + 12 plates. (London: H.M. Stationery Office, 1924.) 15s. net.

Ministry of Agriculture and Fisheries

Banana production is seriously threatened by Fusarium wilt (FW), a disease caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (Foc). In the mid-twentieth century FW, also known as "Panama disease", wiped out the Gros Michel banana industry in Central America. The devastation caused by Foc race 1 was mitigated by a shift to resistant Cavendish cultivars, which are currently the source of 99% of banana exports. However, a new strain of Foc, the tropical race 4 (TR4), attacks Cavendish clones and a diverse range of other banana varieties. Foc TR4 has been restricted to East and parts of Southeast Asia for more than 20 years, but since 2010 the disease has spread westward into five additional countries in Southeast and South Asia (Vietnam, Laos, Myanmar, India, and Pakistan) and at the transcontinental level into the Middle East (Oman, Jordan, Lebanon, and Israel) and Africa (Mozambique). The spread of Foc TR4 is of great concern due to the limited knowledge about key aspects of disease epidemiology and the lack of effective management models, including resistant varieties and soil management approaches. In this review we summarize the current knowledge on the epidemiology of FW of banana, highlighting knowledge gaps in pathogen survival and dispersal, factors driving disease intensity, soil and plant microbiome and the dynamics of the disease. Comparisons with FW in other crops were also made to indicate possible differences and commonalities. Our current understanding of the role of main biotic and abiotic factors on disease intensity is reviewed, highlighting research needs and futures directions. Finally, a set of practices and their impact on disease intensity are discussed and proposed as an integrative management approach that could eventually be used by a range of users, including plant protection organizations, researchers, extension workers and growers.

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Fusarium wilt of banana: Current knowledge on epidemiology and research needs toward sustainable disease management

Induced resistance to Fusarial wilt of banana by menadione sodium bisulphite treatments

Fusarium wilt of banana (Panama disease), caused by Fusarium oxysporum f.sp. cubense, is a soilborne systemic disease which occludes host vascular system. We report here two experiments on resistance induction with banana plants (cv. Dwarf Cavendish) carried out in glass greenhouse with different indoleacetic acid treatments, which are capable of inducing resistance to Panama disease. The results obtained in these experiments suggest that the exogenous application of indoleacetic acid to banana plants induce resistance to Panama disease and that the resistance induction is more effective when performed using low doses and frequent applications. This work seems to confirm the role played by indoleacetic acid according to Beckman’s models as, one of the major defence factors of the host plant in vascular wilt diseases.

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Induced resistance to Fusarium wilt of banana by exogenous applications of indoleacetic acid

Using an authentic sample of 2-hydroxy-9-(p-hydroxyphenyl)-phenalen-1-one, a banana phenalenone-type phytoalexin, we studied its dynamic of accumulation during pathogenesis of banana plants (Musa acuminata (AAA), Grand Nain) inoculated with Fusarium oxysporum f.sp. cubense (FOC), Race 4, the causal agent of Panama disease. The results obtained demonstrate that banana plants treated prior inoculation with menadione sodium bisulfite (MSB), an inducer of plant defenses, are capable of changing the dynamic of accumulation (higher amount and speed of biosynthesis) of this banana phytoalexin, biosynthesized by the banana plant during pathogenesis.

Effect of menadione sodium bisulfite, an inducer of plant defenses, on the dynamic of banana phytoalexin accumulation during pathogenesis.

Variation in nutrition along time and relative chlorophyll content of Leucospermum cordifolium cv. ‘High Gold’, and their relationship with chlorotic sypmptoms

The influence that the application to a soil of different doses of poultry manure may have on nitrate concentrations of the leaching waters and some soil chemical characteristics was studied. The doses of poultry manure that could prevent nitrate pollution under the assay conditions were also determined. The assay was carried out in a greenhouse using 36 lysimeters of 300-l capacity, which were filled with 200 l of an Alfisol Udalf soil each. Treatments consisted of single applications of fresh poultry manure at doses of 45 (T1), 22.5 (T2), 11.25 (T3), 5.63 (T4), 2.82 (T5), 1.41 (T6), and 0.70 (T7) kg m−2, 0.02 g of N per square meter as ammonium nitrosulfate (T8), and a control (T0; not fertilized). Lixiviates were gathered every 15 days from each replication and evaluated for NO3-N, P, Ca, Mg, K, electrical conductivity (EC) and sodium absorption rate. Soil samples were taken at the beginning and at the end of the assay and their physico-chemical characteristics (e.g., water saturation percentage, pH, OM, EC, and available P, K, Ca, and Mg) were analyzed. The amounts of NO3-N leached from the higher doses of poultry manure could represent very important economic losses of N and pose an environmental threat in field conditions. Results suggest that 2.82 kg m−2 of poultry manure or less could be used without negative effects to groundwaters higher than the control. No statistical differences of NO3-N lixiviation between the control and the application of ammonium nitrosulfate were observed. Treatments T1 and T2 produced the highest quantities of Ca, Mg, and K lixiviations. Harmful levels of EC were detected in T1 and T2 lixiviates. Available soil P increased in treatments T1 to T6, while available K and Mg and EC rose with the higher doses of poultry manure.

Marino Fernández-Falcón

Papers

Induced resistance to Fusarial wilt of banana by menadione sodium bisulphite treatments

Induced resistance to Fusarium wilt of banana by exogenous applications of indoleacetic acid

Effect of menadione sodium bisulfite, an inducer of plant defenses, on the dynamic of banana phytoalexin accumulation during pathogenesis.

Variation in nutrition along time and relative chlorophyll content of Leucospermum cordifolium cv. ‘High Gold’, and their relationship with chlorotic sypmptoms

Water Leachates of Nitrate Nitrogen and Cations from Poultry Manure Added to an Alfisol Udalf Soil