Beets, canned, nutrients

Sodium is an indispensable element for some crops (notably sugar beet), can partially substitute for potassium in several crops, contributes to neutralising soil and subsoil acidity, and has a positive effect on soil phosphoms solubiUty. Sodium is an essential nutrient for cattle, and sodium appHcation to soil increases its content in pastures. Sodium nitrate is particularly effective as a nitrogen source for sugar beet, vegetable crops, tobacco, and cotton (qv), and for any crop in acid soils. 

FIGURE 8.2.2 Sugar beets can be used to absorb more nutrients from the soil than is added by fertilizer. They can thus be used to remove excess nuteients left from previous crops. (From Kaffka, S.R. et al, Calif. Agric., 55, 42, 2001. With permission.)... 

Of nutrient chelates in the human diet, oxalates and phytules arc Ihe most common. Oxalic acid, found principally in spinach, rhubarb leaves, beet leaves, some fruits, and mushrooms, is u primary chelator of calcium. Oxalate present in pineapple, kiwifmil, and possibly in other foods, occurs as calcium oxalale. CaCiOj. This compound is in the form of needle-like crystals, known as raphidcs. which can produce painful sensations in the mouth when eaten raw. The effects of oxalic acid in the diet may he twofold. First, it forms strong chelates with dietary calcium, rendering the culcium unavailable for absorption and assimilation. Secondly, absorbed oxalic acid causes assimilated Ca to be precipitated as insoluble salts that accumulate in the renal glomeruli and contribute to the formation of renal calculi. 

Volatilization of toxic compounds may on occasion play a role. For instance, dime-thylselenide (CFI3—Se—CH3) can be formed by degradation of selenomethionine. The rates of volatilization vary between the species considerably. With a supply of 10 gM in nutrient solution, sugar beet plants volatilized < 15 ig Se m leaf area, but rice and cabbage released more than 200 ig Se m per day (Terry et al. 1992). 

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