Quantitative Agrobiological Principles, �Inverse yield nitrogen law,� Mitscherlich yield equation, its interpretation and applicability, �Baule unit.pptx

Quantitative Agrobiological Principles, �Inverse yield nitrogen law,�Mitscherlich yield equation, its interpretation and applicability, �Baule unit

1. Quantitative Agrobiological Principles Inverse yield nitrogen law Mitscherlich yield equation,its interpretation and applicability Baule unit Presented By​ Kamta Prasad Pandey ​ M.Sc. Student Department of Agronomy​ Banda University of Agriculture and Technology, Banda-U.P

2. Agrobiology Agrobiology Term Wilcox Agrobiology  is that division of agricultural science which considers the general external relation of crop plants to their environments, and their mass reactions to growth factors. It thus differs from plant physiology, which considers the inner life processes of vegetable organisms Agrobiology Considers; 1. Perfect environment 2. Maximum yielding ability 3. Growth Factors Agronomy = Maximum yield + Profit Agrobiology = Maximum yield + growth factors + Environment

3. Quantitative Agrobiology Quantitative Agrobiology Concept given by Wilcox in 1928. General and specific Quantitative relation between plant and its growth factor. There are three concept given by  wilcox  :-  1. Mitscherlich diminishing return law 2. Nitrogen constant N- 318 3. Inverse yield nitrogen law 

4. Liebig Law Of Minimum German chemist Justus Von Liebig proposed law of minimum in 1862. “Every field contains a maximum of one or more and a minimum of one or more nutrients. With this minimum be it lime. Potash. Nitrogen, phosphoric acid or any other nutrient, the yields stand in direct relation. It is the factor that governs and controls… yields. Should this minimum be lime …yield…. will remain the same and no longer even though the amount of potash, silica, phosphoric acid etc … be increased a hundred fold.” “Even if all but one of the essential possible elements be present, the absence of one will render the crop barren”.

5. Law Of Minimum

6. Mitscherlich Law “Increase in yield of a crop as a result of increasing a single growth factor is proportional to the decrement from the maximum yields obtainable by increasing the particular growth factor.” Mitscherlich observed that when plant are supplied with adequate amounts of all but one nutrient, their growth was proportional to the amount. Also known law of diminishing return or diminishing yield increment.

7. Mitscherlich Growth Law Graph Diminishing Increment   Y1>Y2 > Y3 >Y4

8. Mitscherlich Equation                           dy /dx = (A - y) C                                      or                                                   log (A-y) = log A- CX Where,  dy  = yield from an increment    dx of the growth factor x.    A = maximum possible yields resulted from optimum supply of all growth factors.    y = yield obtained after any given quantity of the factor x has been applied. C = proportionality constant (efficiency coefficient or factor). C For N = 0.122 ha/ dz               P = 0.6 ha/ dz               K = 0.4 ha/ dz C ∝ 1/Nutrient demond

9. Drawback of Mitscherlich Law C (efficiency coefficient) does not cover all variation of cultivation or production environment. Yield start decrease after  a certain point at this point nitrogen toxicity or antagonistic effect of other nutrients. It means growth curve is quadratic not asymptotic.

10. Inverse Yield Nitrogen Law  Proposed by wilcox (1929)  “Power of growth or yielding ability of any crop plant is inversely proportional to the mean nitrogen content in the dry matter.”  A crop plant with high mean percentage of nitrogen in dry matter has less dry matter production potential than a crop plant with low percentage of nitrogen. 

11. Conti.. Y ∝ 1/Nitrogen (%) in dry matter                   Y  = K/N = 318/N Where,              Y = dry matter  yield (above ground)             N = Nitrogen percentage             K = N uptake (318 lb /acre) Crop​ Yield​ N (%)​ Soya bean​ 20 q/ha​ 2.5​ Wheat​ 40 q/ha​ 1.2​ Sugarcane​ 800 q/ha​ 0.3​

12. Baule Unit (Baule, 1918) Baule suggested that the unit of fertilizer, or any other growth factor, be taken as that among necessary to produce a yield that is 50% of the difference between the maximum possible yield and the yield before that unit was applied. Plants require different amount of nitrogen, phosphorus and potassium, but the amount in pounds of each required to produce a yield that is 50% of the maximum possible yield is called 1 Baule Unit. The values of that baule unit in pounds per acre of N, P2O5 and K2O are 223, 45 and 76 respectively. 1 baule unit of N =  baule unit of P2O5 = 1 baule unit of K2O

13. Conti.. Example of diminishing returns to increasing addition of factor x described by the Mitscherlich Equation Units of growth ​ factor, x ​ Yield (%) ​ Increase in yield (%) ​ 0​ 0​ ​ 1​ 50​ 50​ 2​ 75​ 25​ 3​ 87.5​ 12.5​ 4​ 93.75​ 6.25​ 5​ 96.88​ 3.125​ 10​ 99.9​ 0.098​

14. References —Reddy, S.R. 2019. Principles Of Agronomy. Kalyani Pub. New Delhi.  —Wilcox, Oswin W. 1930. Principles Of Agrobiology Or The Laws Of Plant Growth In Relation To Crop Production. Palmer Publishing Corporation New Yark.

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