Volume 6, Issue 2      April - June, 2018

Modeling the potassium requirements of potato crop for yield and quality optimization


Farheen Nazli1*, Bushra2, Muhammad Mazhar Iqbal3, Fatima Bibi4, Zafar-ul-Hye5,

Muhammad Ramzan Kashif1 and Maqshoof Ahmad6

1Pesticide Quality Control Laboratory Bahawalpur-63100, Pakistan

2Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, Pakistan

3Soil and Water Testing Laboratory, Chiniot, Pakistan

4Mango Research Station, Multan, Pakistan

5Department of Soil Science, College of Agriculture, Bahauddin Zakariya University, Multan, Pakistan

6Department of Soil and Environmental Sciences, the Islamia University of Bahawalpur, Bahawalpur-63100, Pakistan


The intensity, quantity as well as capacity factors are important to predict the amount of nutrient in soil required for maximum plant growth. Sorption isotherm considers these three factors so believed to be one of the most important techniques in soil which control the fate and mobility of nutrients. The field experiment was conducted to find out site-specific and crop-specific potassium requirement for potato crop. The potassium adsorption isotherm was constructed and Freundlich model was used to theoretically work out different soil solution K levels (0, 5, 10, 15, 20, 25, and 30 mg L-1). The K fertilizer doses were calculated against these specific soil solution levels. Field experiment was conducted with seven model based K fertilizer treatments (0, 49, 94, 139, 183, 228, and 273 kg K ha-1) and three replications in Randomized Complete Block Design (RCBD) using potato as test crop.  The results showed that growth parameters like plant height, leaf area and chlorophyll significantly contributed to potato tuber yield. Different yield response models were tested and it was observed that linear plus plateau and quadratic plus plateau predicted equally well the optimum fertilizer K rate both for yield and quality attributes of potato. For maximum potato tuber yield i.e.34.41 Mg ha-1 the economic optimum K was 100 kg ha-1. Optimum fertilizer K rates (at 95 % relative yield) for potato tuber yield, dry matter percentage, protein, starch contents and vitamin C contents were 100, 103, 180, 230 and 200 kg K ha-1, respectively. So, it is suggested that adsorption isotherm technique should be used to calculate site specific and crop specific fertilizer requirements of crops and 100 kg ha-1 is recommended as optimum potassium fertilizer for potato crop. Moreover, the K fertilizer application would improve crop quality that would support the quality based marketing system in Pakistan. 


Keywords: Potato, Quadratic plus plateau, Adsorption isotherm, Yield, Quality

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