Agriculture Reference
In-Depth Information
symptoms appear first on the older leaves (except N and S), while most micro nutri-
ents deficiencies appear on the younger leaves (except Mn). The difference between
the occurrences of deficiencies (from leaves of different age) relates remobilisation
and the phloem mobility of the nutrients. However, more severe deficiencies appear
on the leaves of various ages. The symptoms include general leaf yellowing (N and
S), leaf curling (K) or interveinal chlorosis (Fe, Mn and Zn). A further impact of
deficiency is observed with growth reduction (N and P) or stunted growth induced
by number of marco nutrients due to low supply. Toxicity symptoms show also on
the older leaves (Na, Cl and B); more severe B oversupply induces leaf symptoms
on all leaves on a shoot (symptom of initial B toxicity on picture).
The most common assessment of grapevine nutrient status is determined in the
petioles collected at flowering (Robinson
1992
). Shoot vigour and leaf health are
also important information at flowering, while fruit nutrient concentration indicates
the amount of nutrients removed. Petiole sap concentration has been utilised, but
the information for standard ranges is limited. Another possibility is to monitor win-
ter wood reserves, since it provides a useful information on grapevine reserves and
early information on the nutrient status than the petiole levels assessed in spring.
Assessing nutrient levels in the vineyard soil before planting and during full pro-
duction of vineyards is an additional tool to determine fertiliser requirements. Soil
sampling is usually not taken annually and is most appropriately conducted during
the dormant period of grapevines. The vineyard nutrient cycle is complex; com-
monly the main movements of nutrients in a vineyard system are the removal by
the crop, the recycling of organic material and the input of fertiliser (Bauer
2002
).
Nutrients are removed by the soil by the grapevines and the covercrop, the later
can be important for bringing nutrients from deeper soil levels (nutrient mining).
The removal by the crop is less if part of the grape material is brought back to
the vineyard via pressings. The nutrients present in the green and root mass of the
covercrop, together with the prunings can also be recycled. The application of or-
ganic and mineral fertiliser fills the gap of nutrients brought about by the removal
of grapes and losses from the soil by leaching.
Vine nutrition is important for grape production, with nutrients have several cru-
cial functions in vine development and vary in mobility and winter storage. Both
yield and grape composition is influenced by nutrient supply (mobilisation and up-
take). The information on vine and (soil nutrient) status is essential for vineyard fer-
tiliser management, with the application of fertiliser needs to consider the vineyard
nutrient cycle and root dynamics.
Irrigation
In many grape growing regions of the world, irrigation is not permitted. Growers
nevertheless are astutely aware of the plant water requirements as a yield limiting
component and monitor soil or plant based signs of water stress. Where it is per-
mitted, irrigation is an important component of vineyard management, particularly
