By Ujwala Ranade-Malvi
Anyone who has visited a coffee or tea estate is invariably a proud owner of a huge archive of beautiful snapshots. These images brilliantly capture the enchanting scenery, the verdant green tiered shade trees, busy bumble bees pollinating the delicate coffee flowers, robust red bunches of ripe berries ready to be picked, brightly dressed skilful laborers hand picking the coffee beans, pulping of the coffee in large pulping machines and patio drying of the processed coffee.
These very essential “why, what, who, which and when” snapshots of the estate help put the estate and its operations into perspective.
A similar exercise is undertaken by plantation owners. They too take breathtaking pictures of their own estate. But more often than not, they “click” a little deeper, beyond what meets the eye. They take snapshots of the health of the soil and snapshots of the ionic-mineral content of the coffee leaves. Why? Here’s why.
Most coffee and tea estates are located in the ecological hotspots of the world. Plantations are biotic microcosms where multitudes of plants, animals and microbes live in mutual harmony. Every planter knows that even a slight change in the conditions of the soil can be disastrous for this micro-ecosystem. If he has to maintain and sustain this environmentally sensitive area called his plantation, efforts have to be made to ensure the health of the soil matrix. He is also aware that since his livelihood depends on the final yield, efforts have to be made to ensure the health and productivity of the coffee/tea bushes. Hence, more than aesthetic snapshots, most progressive planters are interested in biochemical, biological and ionic snapshots; the snapshots of the very essential “why, what, who, which and when’s” of the estate to put the overall health of the plantation into perspective.
Tea and coffee plantations come with their own set of inherited problems. Indiscriminate use of water and imbalanced fertilizer application has resulted in the decrease in inherent fertility, reduced soil productivity, reduced nutrient use efficiency, higher incidence of pests/disease and a generalized failure of the planter to make money! Ironically, these problems are seen in both organically and inorganically managed estates with a somewhat higher incidence seen in organically managed ones. This not only affects the planter at his personal level but also has a profound effect on the producing country as GDP’s are often tightly tied into coffee/tea. To optimize production levels and to minimize production costs, it becomes critical to bridge the gap between current soil status and crop requirement. Prognostic soil and tissue audits are an excellent analytical tool that can be called upon to understand and manage soil and crop health.
Snapshots of the soil
A soil audit gives a snapshot of the physical, biological and chemical profile of the soil at the time of sampling and analysis. There are various levels of soil audits. The most basic one will test for pH, soil texture and electrical conductivity which throw light on the physical condition of the soil. A more detailed soil test will analyse for the 16 nutrients essential for plant growth. This includes: nitrogen (N), phosphorus (P) and potassium (K), which are called the major nutrients followed by calcium (Ca), magnesium (Mg) and sulfur (S) which are called the secondary nutrients and finally the ever essential six micronutrients, iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron( B) and molybdenum (Mo). This analysis gives us an indication of what is available in the soil and helps us predict nutrient deficiency that can occur in it. Besides these nutrients, some laboratories will test for other important parameters like aluminum, total carbonates, water holding capacity, field capacity, organic matter and cation exchange capacity. A complete soil audit should influence management decisions on quantity and quality of fertilizers to use to fulfill the production levels that the planter desires.
One parameter that deserves a little more discussion is pH. The pH of the soil is called the master variable. It indicates how acidic or basic the soil is. It is the controlling factor for the availability of nutrients in the soil solution. It is the inverse log of the hydrogen (H+) content in the soil. The higher the H+, the lower the pH, the more acidic the soil. A pH of 6.5 to 7.5 is an agriculturally optimum range in which all nutrients are made available (see the green bars in figure 3). However, most plantation crops tend to be cultivated in acidic soils with a pH range of 4.5 to 6.5. In this range, some nutrients are not available to the crop as is seen by the orange/red bars on Figure 3. A soil audit followed by a good nutrient management program will take this factor into account and adjust the type and quantity of fertilizer inputs accordingly.
As a rule of thumb, soil analysis should be done between 1-2 times a year, but most critically at the start of any fertilizer program.
Snapshots of the leaf
Tissue/leaf analysis is done in conjunction with soil analysis to get a picture of the soil-plant continuum. Soil tests measure levels of specific nutrients in a soil. They cannot indicate whether plants growing in that soil are able to take up these nutrients. Linear logic holds that whatever is put onto the soil will be available to the plant. Unfortunately, the plant’s ability to take up adequate nutrients is influenced by many factors such as soil temperature, compaction, moisture, nutrient balance in the soil and plant genetics and variety. A soil test cannot accurately account for all of these factors. A progressive grower must use plant analysis if he expects to identify, understand and manage the nutrient use efficiency and needs of his crop.
Tissue audits also have different analysis levels. Some laboratories will diagnose the principal nutrients like: N, P and K. Some may add in Ca, Mg, S and micronutrients like Fe, Mn, Zn and Cu, depending on what the planter requests. Few laboratories test for two crucial elements-Boron (B) and Molybdenum (Mo). These anions are critical for the reproductive stages of all crops and every planter must insist on getting these numbers analysed. Tissue analysis will analyse nutrients levels present in the growing leaves and will determine which are falling short. A deficiency of any nutrient will express itself visually on the leaf. However, once visual symptoms appear on the leaves, top yields and quality are severely compromised. The advantage of regular tissue audits is to detect problems before they cause yield damage. Corrective measures can be taken immediately to avert such problems and help eliminate crop failures and yield shortages. A rule of thumb would be to analyze leaves at the start of the vegetative stage to see if the plant has enough of the correct nutrients to put out enough leaves to kick-start the photosynthesis process. This should be followed by analysis at the beginning of flowering stage to ensure that all nutrients are present for timely reproduction.
Progressive growers are snapshot happy
There are hundreds of laboratories out there that do a great job of analysis. The caveat to this is that each lab has its own protocol of extraction of nutrients, method of analysis, equipments used for analysis, grade, brand and purity of chemicals used. Hence analysis data and interpretations will vary from lab to lab. It would be unfair to compare results between laboratories unless one is 100% sure that all the above parameters are the same. Most reputable labs will use the methods and protocols laid out by the Association of Official Analytical Chemists (AOAC). It is advisable to choose one laboratory and stick with that laboratory to get standardized and uniform analysis year after year to help better manage farm fertility index.
Farming has come a long way from being just an honorable profession to an extremely highly-valued and high-risk profession. Agriculture is not everyone’s cup of tea (coffee). It is a tough job that that needs grit, a high amount of energy, 100% submission to the rules of nature and 100% perseverance. The climb is steep, the hurdles are plentiful and the rewards are not predictable, especially for a high value crop like coffee or tea. Weather aberrations and market prices are largely out of the planter’s management sphere. What he can manage are basic resources like soil and crop. We all have heard the management maxim “you can’t manage what you don’t measure”. Measuring and then managing main resources like soil and crop will be critical to the growth of this sector.