Soil readily retains positively charged ions Mineral particle Positively charged nutrient ions minera Plant root phenolate Ne Fig 15.10 the negatively charged surfaces of soil mineral particles and humus help retain positively charged nutrientsSoil readily retains positively charged ions humus Positively charged nutrient ions Plant root mineral Mineral particle phenolate Fig 15.10 the negatively charged surfaces of soil mineral particles and humus help retain positively charged nutrients