Growing on course textured sandy soils low in O.M. (organic matter).

These soils don't hold much in reserve, their ability to store cations is diminished, available soil moisture is quickly depleted as demand increases in June - August.

Soils with low buffering capacity, (inability to resist changes in pH). Usage of ammonium based fertilizers on sandy soils with low O.M.

Soils should ideally be slightly acid and around 6.5 - 6.8 pH. PH > 7 reduces availability of Mn, Ca, Zn, and B. pH < 5.5 can reduce availability of Ca, Mg and increase Mn availability to a toxicity (measels).

Inadequate soil microbial activity

Poor breakdown of mulched material may be a sign of a carbon starved ecosystem. A weak microbe population can result from less than ideal pH.

Excessive soil wetness, poor drainage part of the year - winter injury & frost damage, compaction

Foliar applied nutrients (e.g. urea) may help overcome poor or inadequate root performance or help a tree recover from a trauma event.

Renovation of acreage

pH adjustments and phosphorus reloading of soils best carried out while trees are gone. Adjustments to pH, potassium, phosphorus and other soil applied nutrients made according to soil test recommendations.

Excessive use of macronutrients, micronutrients

Excessive K interfering with uptake of Mg on Mg deficient soils, excessive P reducing uptake of Zn. Possible boron toxicity from excessive use.

Adding large amounts of organic materials with a high C/N ratio (e.g. wood chip mulch)

Soil microbes use a high % of available N to build up their numbers to take advantage of the carbon contained in the organic material.

Drought and sustained moisture deficit during growing season and into fall

Repeated and sustained episodes of moisture deficit can inhibit root growth (spring, fall) and roots ability to absorb various nutrients.

Poor sod growth

Sod health contributes significantly to overall nutrient cycling and soil health

History of nutrient deficiencies

Some soil types are alkaline in nature with a high pH on coarse sandy soil with a low O.M. or areas with natural shortages of micronutrients like boron or zinc.

Change in cultivar mix and tree density

Some of the newer cultivars (hard varieties) require higher N status as determined by leaf analysis.

Higher yields

Crop removal of N, Pand K is directly related to crop size. This does not necessarily imply an increase in the use of N.

Fruit quality problems

Too much N can be as bad as too little. Too much N can degrade postharvest life. Lack of K can inhibit the fruit size, colour and tree hardiness.

Dramatic reduction in crop load (off year or frost has taken out bloom), or heavy pruning

Adjustments have to be made to compensate for lack of nutrient removal. 25 bins will remove approximately 14 kg N, 22 kg K, 3.5 kg P. Adjust N stands for nitrogen in this case, for degree of pruning.

Cultivars with a high probability of exhibiting calcium related disorders

Management changes to improve absorption pickup and delivery of adequate calcium to the crop e.g. may involve changing thinning or irrigation practices.

Excessive vigour, pruning and training costs are too high

Excessive growth and luxury consumption of nutrients can come at the expense of crop quality.

Unusually high disease expression

Lush growth can enable fireblight to be more destructive.

Trees established on fine textured, deep silts, loams and clay loams. Soils having High O.M.

Every percentage point of O.M. results in approximately 20 lb/ac plant available N, greater ability to store and provide the essential nutrients, higher cation exchange capacity

Soil high in buffering capacity, stable pH

Soils not easily subject to changes in pH don’t readily change their ability to release nutrients. Soil microbes continue to function at capacity.

Adequate microbial activity as evidenced by rapid breakdown of mulched materials, prunings

Microbes work for free, indicator of healthy orchard ecosystem.

Good site, deep friable soil, no drainage problems

Roots function well year round.

Adequate available soil moisture, irrigation scheduling

Superior production of new roots - better absorption of nutrients and less water cycling out of crop to leaves when trees are irrigated.

Tissue, soil analysis on regular basis - adjusting to a standard based on calibration work

Less likelihood of getting completely off track with nitrogen, potassium and micronutrients.

No dramatic changes in use of large volumes of O.M. (therefore C/N ratios) (e.g. mulching with wood chips, straw)

Added nitrogen not required to compensate for large changes in carbon available in orchard ecosystem.

Sod growth good

Balanced feeding of sod helps nutrient cycling and O.M. production.

Monitoring and adjusting supply (N,P,K) to fulfill yield/growth expectations (adequate soil reserves of phosphorus)

Positive correlation between yield and removal of N, P, K

Growing cultivars that don't generally express calcium related physiological disorders

Diminished need to adjust cultural practices to compensate for inability to pick up and distribute adequate amounts of calcium to crop.

Maintenance application of foliar grade fertilizers (N,P,K + micros) in combination with soil/tissue testing

Can overcome short term needs.

Stress control on trees e.g. irrigation, thinning, summer pruning, cropload management, mulching soils - no serious trauma events - winter injury, frost etc.

Absorption and distribution of essential nutrients is done by the tree with greater efficiency when trees are relieved of cyclical stress factors

Adequate shoot growth. 20 - 30 cm/yr., moderate pruning needs, consistent cropping

Shows balance between fruiting habit and new growth. Grower is able to control pruning costs.

Good fruit set and need for thinning

Adequate fruit set can be a good sign of balanced feeding. Need for N is highest early in the growing season. Tree reserves of N essential for first 3 weeks.

Fruit quality, fruit size, and storage potential meeting expectations

Good indicators of balanced program including crop nutrition and orchard management in general.