write 5 structures needed in a small-scale nursery​

Sagot :

Answer:

High rainfall areas are best avoided. However, the season    in which the precipitation occurs is important. Heavy spring rains  can  delay  spring  operations  such  as  adding  soil  amend-ments,  starting  a  cover  or  green  manure  crop,  or  sowing  tree  seed.  Summer  rains  tend  to  be  a  problem  only  when  they          occur  as  cloudbursts  and  result  in  flooding,  erosion,  or  seed-ling  wash-out.  Frequent  summer  rains  may  be  detrimental,  however, because rains may disrupt stock hardening processes already  induced  by  withholding  irrigation.  Areas  with  heavy  winter  rains  should  be  avoided;  heavy  rain  saturates  nursery      soil to the point of hindering lifting, damaging soil structure,   and causing flooding and erosion.Wind.—Areas  with  frequent,  long-lasting,  high-velocity winds-particularly where humidity is low and winds are drying and from the east—should be avoided. Winds will affect irriga-tion application and uniformity and may result in soil movement. High  winds  can  desiccate  seedlings,  and  soil  carried  by  winds  can  blast  stems  and  foliage.  Wind  can  restrict  spraying  of  pesticides,  cause  tree-seed  cover  to  be  blown  away,  and  dis-place or scatter seedbed mulches.2.2.2.2 SoilPerhaps the most important factor in establishing a nursery  is the correct choice of soil (see chapter 6, this volume). Other site  features,  including  fertility,  moisture,  and  microclimate,      can be manipulated by the nursery manager [2], but moving or significantly modifying large masses of soil is, at the very least, impractical  and  costly.  An  intensive  soil  survey,  coupled  with      representative soil sampling, will help the selection team choose the  site with the most suitable soil.Texture.—Sandyloams  or  loamy  sands  with  good  drain-age  are  excellent  for  nurseries.  Light  soils  can  be  worked  in  weather  conditions  too  wet  for  heavier  soils—an  important  consideration  in  the  Northwest.  The  content  of  clay  and  silt  (particles  <  0.05  mm  in  diameter)  in  the  soil  should  be within   15 to 25%.Depth.—The  top  4  feet  of  soil  should  be  free  of  claypan,  hardpan,  shale,  iron  concretions,  calcareous  substrata,  or  mot-tled gley layers [9]. Without artificial drainage, this depth seems a reasonable  minimum;  where  artificial  drainage  has  been  in-stalled,  however,  a  minimum  clear  soil  depth  of  2  feet  is probably  acceptable  [8].  The  top  18  inches  of  soil  should  be    free  of  stones,  which  are  expensive  to  remove,  make  the  soil  difficult to work, and interfere with nursery cultural practices

Explanation: