During KSS WONDERFUL DISCUSSION WITH shri jkp sir ESSENTIAL ELEMENTS, MOBILITY AND pH EFFECT |
essential element - an element required by plants for normal growth, development and completion of its life cycle, and which cannot be substituted for by other chemical compounds. 17 ELEMENTS ARE REQUIRED BY PLANTS 3 supplied naturally by air and water- comprise the bulk of the plant C, H, 0 6 macronutrients - required at 0.1 to 6% of the dry weight of plants N, P, K, S, Ca, Mg 8 micronutrients- required at 1 to 300 ppm of the dry weight of plants Fe, Zn, Cu, Mo, B, Mn, Cl, Ni Cl and Ni are ubiquitous - hence, will not be addressed in detail The essential elements can be easily remembered by a catch phrase such as C. HOPKiNSCaFe, CuB, Mn, C.l. MoNiZnsky, Mgr NUTRIENT MOBILITY Two directions of movement in plants 1) acropetal - means towards the apex; transport up the in xylem 2) basipetal - means towards the base; transport down in the phloem Two classifications of nutrient mobility 1) mobile - moves both up and down the plant by both acropetal and basipetal transport (in both the xylem and the phloem). Deficiency appears on older leaves first. N, P, K, Mg, S 2) immobile- moves up the plant by only acropetal (in the xylem) transport Deficiency appears on new leaves first. Ca, Fe, Zn, Mo, B, Cu, Mn EFFECT OF pH The pH determines solubility in the soil 1)more available at low pH (below 5.5), and less available at high pH. Fe, Zn, Cu, Mn, B 2) more available at high pH (above 6.5), and less available at low pH. N, K, Mg, Ca, S, Mo 3)more available at intermediate pH (6-7) P Ideal pH slightly acid: a) around 6.5 for field soil b) around 5.5-6.0 for artificial growing media made with peat moss or composted bark |
FUNCTION OF NUTRIENTS | |||||||||||||||||||||||||||||||||||||||||||||
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TISSUE CONCENTRATION, DEFICIENCY SYMPTOMS AND FERTILIZER SOURCES | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
*chlorosis = yellowing; necrosis = browning; interveinal = between the veins **micronutrients are often applied as a multi-micronutrient mix; ex. STEM, PERK, Micromax | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
NUTRIENTS WITH SIMILAR DEFICIENCY SYMPTOMS | |||||||||||||||
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NITROGEN CYCLE |
 WAYS IN WHICH NITROGEN IS LOST FROM THE SOIL 1) leaching (especially nitrate which is negatively charged) 2)plant absorption 3)microorganisms consume (see C:N ratio next page) 4) denitrification |
NITROGEN CONVERSIONS | |||||||||||||||
NITROGEN REACTIONS mineralization or ammonification -the conversion of organic nitrogen (in the -NH2form) to inorganic nitrogen (in the NH4 form). - the speed of conversion depends on the C:N ratio (see below). nitrification - a two step process converting ammonium to nitrite, then nitrite to nitrate. - the soil bacterium Nitrosomonas converts ammonium to nitrite - the soil bacterium Nitrobacter converts nitrite to nitrate - this occurs very quickly so little ammonium (which can be toxic if high) and virtually no nitrite (which is highly toxic) accumulates in the soil. denitrification - the conversion of nitrate in the soil to gaseous nitrogen that escapes into the atmosphere. nitrogen fixation - the conversion of gaseous nitrogen to ammonia. - only nitrogen fixing microorganisms can cause nitrogen fixation; some form symbiotic relationships with plants (see table below) CARBON:NITROGEN (C:N) RATIOS IN ORGANIC MATTER C:NRatio - proportion of carbon to nitrogen present in organic matter. a)high C:N ratio- wood, sawdust, uncomposted bark - microbes use up all nitrogen in organic matter when consuming carbon, - then the microbes use up the nitrogen in the soil b)low C:N ratio - manure, bone meal, fish emulsion, organic fertilizers - microbes consume carbon, - then release excess nitrogen from the organic matter into the soil - thus, low C:N organic matter acts as an organic nitrogen fertilizer | |||||||||||||||
MICROORGANISMS THAT CAN FIX NITROGEN
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