FANR 3060 1st EditiomLecture 17Outline of Last LectureI. SoilChemistryII. CECs/AECsOutline of Current LectureI. Plant Growth FactorsII. Plant Uptake of NutrientsChapter 6I. Plant Growth Factorsa. Any enivronmental factor that affects or determines plant growthi. Water, air, light, nutrientsii. If it determines, it’s an essential factor b. Essential elementsi. Plants can’t live without itii. Macronutrients1. “fertilizer” elements2. N, P, Kiii. Secondary elements1. Ca, Mg, Siv. Micronutrient cationsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. Fe, Mn, Cu, Zn, Niv. Micronutrient anions1. B, Cl, Moc. Soil Fertilityi. Capacity of soil to supply nutrients to plant over growing season (or some amount of time)ii. Absence of other potentially limiting soil chemical features1. Salts, excess acidsd. Liebigi. Believed there were multiple growth factorsii. Came up with the “law of the minimum”iii. Considered the “father” of chemical fertilizersiv. Searched for limiting factors1. This is how we manage crops2. Water, pests/diseases/weeds, nutrients3. Figure 6.1II. Plant Uptake of nutrientsa. Elements must be soluble in soil solutioni. Taken up passively or actively1. Passive: absorbed by root as water flows in2. Actively: transported across cell membrane into plant b. Solubility = availabilityi. Over entire growing seasonii. “fertility”c. Total amount in soil is not the determining factor i. Most of any nutrient in soil is tightly bound 1. Not available or soluble2. About 90% of nutrients in soilii. Fig 6.2iii. Each element has individual chemicals that determine solubility 1. Affected by minerals in soil, pH, other factorsIII. The Nitrogen cyclea. Fig 6.3b. N is a major component of amino acids (proteins)c. Often most limiting factori. High amounts are requiredd. Availability influenced by soil organismsi. Bacteria, fungi1. Compete with plants for Ne. Humus is a large reserve of Nf. Legumes = rhizobiumi. Adds N back into soilii. Crop
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