Applied and Environmental Soil Science

Review Article

Agroforestry and the Improvement of Soil Fertility: A View from Amazonia

Table 1

Levels of nutrients, organic matter, and acidity, by depth, in homegardens and savanna soils in Araçá Indigenous Land, Roraima, and Brazil. Homegarden values followed by * or ** are statistically different from savannas, with and , respectively, by Mann-Whitney test ( -test).
Savanna ( )New homegardens ( ) (0–10 years-old)Estabilished homegardens ( ) (15–35 years-old)Old homegardens ( ) (40+ years old)
P (mg Kg−1)
 0–10 cm2,114,3**26,5**43,7**
 10–20 cm1,18,5*12,2**37,9**
 20–30 cm0,67,5*7,5**31,2**
K (cmolc Kg−1)
 0–10 cm0,070,080,11*0,18**
 10–20 cm0,060,080,10*0,15**
 20–30 cm0,060,070,10*0,13**
Ca (cmolc Kg−1)
 0–10 cm0,320,66*1,48*1,93**
 10–20 cm0,220,241,02*1,41**
 20–30 cm0,170,180,63*1,03**
Mg (cmolc Kg−1)
 0–10 cm0,160,180,300,48**
 10–20 cm0,090,100,24**0,33**
 20–30 cm0,060,070,18*0,28**
Fe (mg Kg−1)
 0–10 cm25,221,439,8135,6*
 10–20 cm22,717,837,4104,4*
 20–30 cm20,312,626,581,0*
Zn (mg Kg−1)
 0–10 cm1,93,112,9**13,9**
 10–20 cm2,11,58,11**11,6**
 20–30 cm2,61,48,63**11,4*
Mn (mg Kg−1)
 0–10 cm22,432,429,9140,6
 10–20 cm16,723,918,0224,7
 20–30 cm15,323,414,9318,5
Cu (mg Kg−1)
 0–10 cm0,860,741,701,17
 10–20 cm0,870,671,371,17
 20–30 cm0,840,621,281,13
Organic matter (g Kg−1)
 0–10 cm12,912,220,627,6**
 10–20 cm10,07,914,619,5*
 20–30 cm8,36,910,414,3*
Al (mg Kg−1)
 0–10 cm0,130,070,080,05*
 10–20 cm0,170,120,090,08
 20–30 cm0,190,110,110,10
pH (H2O)
 0–10 cm5,345,395,485,45
 10–20 cm5,165,285,395,49
 20–30 cm5,135,295,305,32