Soil and leaf tissue analysis in banana production

Soil testing can be used to assess pH, organic matter content and cation exchange capacity (CEC), thereby indicating nutrient availability and the nutrient retention characteristics of the soil.

Soil analysis

Soil analysis can be used to assess levels of soil potassium and phosphorus and also to provide an indication of likely cationic imbalances, e.g. K:Mg:Ca ratios. However, it is not a good indicator of nitrogen requirement. Therefore, soil testing alone does not provide enough information to ensure accurate nutrition.

Leaf tissue analysis

Leaf tissue analysis helps monitor crop needs throughout key periods of growth. In season analyses – carried out at the same growth stage – will help the producer build up a clear picture of the plantation’s nutrient status and needs, and highlight where adjustments need to be made to current fertilizer programmes.

Leaf tissue analysis should also be used to diagnose or confirm nutrient deficiencies, particularly where visual symptoms are confusing, not visible, or where multiple nutrient deficiencies occur. It is important to ensure that tissue analysis follows standard procedures. There are two commonly accepted procedures adopted in different producing countries. Both analyze the middle lamina or inner part of the blade of leaf number 3 – the third fully expanded leaf on the plant at flowering or shooting (see photo below).

The most widely practiced method (IRS, International Reference System) analyzes the inner leaf area, but it is also acceptable to assess the nutrient status of the whole transversal strip.

It is important to be aware of which of these methods has been used as the accepted optimum leaf nutrient standards vary according to the analysis (Table 4) and the exact section in the leaf strip that is tested.

Macronutrients
Optimum Leaf Analysis Standards (%DM)
Growth Stage: Inflorescence Emergence
Inner Area of Lamina 3
Source	Country	N	P	K	Ca	Mg
Martin - Prevel - 1978	Africa	2.7 - 3.6	0.18 - 0.27	3.5 - 5.4	0.25 - 1.2	0.27 - 0.60
Rosero Ruano - 2000	Costa Rica	2.6 - 3.0	0.20 - 0.25	3.7 - 4.0	0.7 - 0.9	0.27 - 0.35
Espinosa and Mite - 2002	Latin America	>2.6	>0.2	>3.0	>0.5	>0.3
Whole Transversal Stripe
Source	Country	N	P	K	Ca	Mg
Reuter and Robinson (1997)	Australia	2.8 - 4.0	0.20 - 0.25	3.1 - 4.0	0.8 - 1.2	0.30 - 0.46

Tests are most commonly carried out on large suckers with an adjoining mother pseudostem, during periods of active growth. Normal practice is to sample when the mother is in post flower formation or shooting stage. The tables on this page give nutrient standards for macro and micro nutrients based on analyses carried out on plant tissues taken at the growth stage described above.

Micronutrients
Optimum Leaf Analysis Standards (ppm)
Growth Stage: Inflorescence Emergence
B	Cu	Fe	Mn	Mo	Zn
20-40	7-20	81-150	200-300	1.5-3.2	20-30
Ref: R&D dept from Chiquita for Grand Nain (Central America) Mo Standards from Lopez & Espinosa - 2000

Nutrient ratios

Soil and leaf tissue analyses should also be used to assess nutrient imbalances. Where the critical values for any one of K, Mg and Ca are exceeded, then uptake of other cations can be affected.

This is graphically illustrated in Venezuelan trials where excessive use of potassium depressed yields through restricting calcium uptake. When calcium was applied in-balance alongside these high levels of K, yields increased.