Of 1 g kg dry weight micronutrients

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: by green) •  yellowing can also result from Fe deficiency because Fe is needed for chlorophyll synthesis •  N can easily move around the plant body; Fe cannot; in iron deficiency, growing leaves tend to show symptoms before older leaves that are finished growing defining required nutrients: hydroponic experiments •  Defining nutrients required for plant growth: hydroponics - research began in the mid 1800s on macronutrients •  Most recent work (much more precise control needed to demonstrate micronutrient requirements) - 1983 defined Nickel as an essen<al micronutrient •  see expt in Fig. 36.3 hPp:// Expandable_Hydroponics_System_from_Junk_Flood_an/ Soil •  provides: –  mineral nutrients –  water –  oxygen for roots soil horizons •  A: crucial for growing crops; leeching by water movement removes nutrients to B horizon, where they are oMen not available to plant roots; also contains decaying organic maPer •  can be lost by erosion [1930s Dust Bowl in Midwest, Great Plains] •  sand: air space plen<ful but doesn't hold much water •  clay: doesn't have much air space but binds minerals well •  loam: contains adequate amounts of sand, silt (fine par<cles), and clay - best for growing plants •  B: contains leeched minerals but liPle or no decaying organic maPer; some plant roots can reach B •  C: bedrock; plant roots typically do not reach C •  oMen essen<al for mineral availability to plant roots –  many crucial ions posi<vely charged (K+. Mg2+. Ca2+, NH4+); clay is nega<vely charged •  H+ from this aqueous reac<on in soil CO2 + H20 <- > H2CO3 <- > H+ + HCO3- •  •  •  •  binds to clay strongly and displace weaker binding mineral ca<ons (posi<vely charged ions) This is called ion exchange –  The displaced mineral ions are thus more available for plant uptake However, crucial nega<ve ions (anions): Nitrate (NO3- ) and Sulfate (SO42- ) cannot be maintained in the A soil horizon in the same way; leach very easily => most A horizon N is in the form of decaying organic maPer (slowly breaks down and releases NH4+, plants uptake this) clay fer<lizers in agriculture •  agricultural plant growth rapidly depletes nutrients •  most common elemen...
View Full Document

This note was uploaded on 10/02/2013 for the course BIO 201 taught by Professor True during the Spring '08 term at SUNY Stony Brook.

Ask a homework question - tutors are online