SOIL FERTILITY STATUS OF NCHIMA ESTATE —Malawi—

A.E. Hartemink 1990

ISRIC LIBRARY Wl - 1990.01 01 Wageningen The Netherlands

ISRIC LIBRARY

ÏU+L ^>-Ol Wageniogen, T h . Netherlands

SOIL FERTILITY STATUS OF NCHIMA ESTATE WÊÊ - M a l a w i - WÊÊÊ

A.E. Hartemink 1990

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9QIL FgflTLTTY STATU9 OF NCflIMA B3TATE IN 1997

1 INTRODUCTION

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2 SOIL FSETTLITY STATUS 2.1 General Trend

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2.2 Tea and the Soil Fertility Status

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2.3 Coffee and the Soil Fertility Status

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3 RECOMMENDATIONS

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3.1 Tea

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3.2 Coffee

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ANNEXES: Annex 1 Analytical Data of Samples

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Annex 2 Keys to Soil Depth, Soil Reaction Classes and General Ratings of Soil Fertility Parameters •'

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1 i

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i imvwmw This report concerns an interpretation of the soil analysis report of Nchima Estate with reference to tea and coffee cultivation. It was written at the request of Mr. K.P. Legg by Mr. A.E. Hartemink in August 1990. The soil analysis report gives the data of 74 samples taken from selected fields in August 1987. The purpose of this report as to provide the Nchima management with information about the soil fertility conditions of the fields and to provide them with some fertilizer recommendations for tea and coffee. Hereto the data were compared with the chemical soil requirements of tea and coffee. Constraints in the interpretation were: -unknown depths and methods of sampling -^unknown methods for soil analysis -CEC and texture are not determined -data are three years old Especially this latter constraint made that detailed and actual valid recommendations on the fertilizing management of individual fields could not be made properly.

2 .gpH, mniwy spws 2.1 General Trend The analytical data of the soil samples are given in Annex 1, a summary with the highest and lowest values of the top- and subsoil is given below: Summary of Chemical Data of Soils at Nchima Estate, Highest and Lowest Values. depth pH H20 Avail. P ppm

Exchangeable Cation meq% K Ca Mg

Loss on ign. %

topsoil 3.8-5.5 tr. - 137 0.03-0.79 0.18-0.84 0.03-0.65 4.1-12.3 subsoil 4.3-5.8 tr. - 27 0.20-0.62 0.19-0.94 0.11-1.31 3.1-13.4

Wi£h only a few exceptions can be stated that the soils of Nchima Estate have an extremely to very strongly acid soil reaction (pH). Exchangeable cations are low for potassium, very low for calcium and very low or low for magnesium. Available phosphorus levels tend to vary considerably but most soils are not very well supplied with this element. In some soils it is completely absent. Rirthermore in very acid soils phosphorus is precipitated into compounds of low solubility. The lower the pH, the higher the exchangeable aluminium level and the larger the P-fixation. The organic matter contents (expressed in loss on ignition) are satisfactorily though the method applied for analyzing tends to overestimate the contents. Remarkable is the little difference in organic matter contents of the top- and subsoil. 2

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The chemically richest soils are in the fields: Abram 1&2, Chil, Nankh, Oof f and Kab i/ii/iii/iiig. In these soils the pH is generally higher (between 5.0 and 5.5) and potassium levels are generally moderately. Levels of phosphorus, magnesium and calcium are low. The chemically poorest soils are in the fields: 4, 6, 7, 10, chiwale, nkolokosa, no.l top and no.3. In these fields the soils have an extremely low pH and low or very low levels of exchangeable cations. The low pH may be due to continuous cultivation without replenishing of nutrients or as consequence of applying fertilizers with a net acidifying effect.

2.2 Tea and the Soil Fertility Status The fertility conditions of many soils are favourable for tea cultivation despite the fact that the soils are very strorgly acid. It is very likely that with these soil reactions the aluminium availability is high and as tea is an aluminium accumulator, the acid soil properties are generally favourable. Nevertheless, attention must be paid to soil pH, because increasing soil acidity may induce deficiencies, mainly of potassium and phosphorus, sometimes magnesium and molybdenum. Moreover an increasing soil acidity inclines losses due to leaching and it reduces the efficiency of fertilizer applications. However, liming of tea soils is not recommended as calcium requirements of tea are rather low and lime hinders the uptake of potassium. It is assumed that the organic matter is able to release sufficient nitrogen after the onset of the rains when it is mineralizing. This nitrogen flush does not cover the entire needs of the tea plants in the growing season and nitrogen fertilization is therefore required some period after the onset of the rains. An application of 90 kg N/ha per year is considered as the minimum. The phosphorus levels are very much varying which explains the variable response to phosphorus explanation in tea in the Cholo district as reported by the TKF of Central Africa (1979). Nevertheless an application of 30 kg of P205 (13 kg P) should be given annually per hectare to all areas where NPK fertilizer is not used. In some fields where phosphorus is absent (no.4, chil, nankh, nched, trott etc.), the application may be increased to 50 kg of P205 per hectare. The potassium levels of the soils are not sufficient to cover the requirements of the tea crop. The onset of potassium deficiency will be hastened by the use of of nitrogen fertilizers alone, particularly sulphate of ammonia or CAN, and by removal of prunings from the field. To prevent potassium deficiencies affecting yield, potash fertilizer should be applied to all tea on soil of pH 5.8 and lower. In other words, all tea of Nchima Estate requires potash fertilization. Magnesium levels are very low in all soils of Nchima Estate. Usually there is no evidence of any need for magnesium fertilizer in tea. Magnesium deficiency arises frequently as a result of poor root development due to lack of potassium, not because of lack of available magnesium in the soil. It was found that correction of the potassium deficiency leads to the disappearance of the magnesium deficiency also.

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2.3 Coffee and the Soil Fertility Status The pH (or soil reaction) of most soils is too low for Cofféa arabica cultivation. With these soil reactions aluminium becomes readily available are!. may be taken up by the coffee trees in toxic amounts. It is therefore that the crop is rarely grown on soils with a pH below 4.5 where aluminium toxicity could be serious. At Nchima, liming is required for successful coffee cultivation. Provided that all the conditions are right for the coffee tree -management, soil moisture and no elements are deficient- then the available nitrogen has the greatest effect on yield. Under most conditions where coffee trees are grown without shade and produce heavy crops, regular applications of nitrogen fertilizer are essential. Conversely, coffee growing under heavy shade rarely responds to the application of nitrogen fertilizer. As the soils of Nchima are not very well supplied with other major nutrients (e.g. potassium), nitrogen fertilization only . induces nutrient imbalances and hence deficiencies. Moreover the crop becomes susceptible to diseases. The coffee tree requires comparatively little phosphorus and coffee appears to have a remarkable ability to take up the amount of phosphorus it needs even when the level in the soil is low. However, for root growth and flower development an adequate level of available phosphorus is vital. As most soils of Nchima have levels below 10 ppm, phosphorus applications is required to new plantings, and for productive plantings after the harvest period is complete. Like many tropical fruit crops, coffee has a high level of potassium uptake. Potassium usually becomes inadequate when the trees are bearing a heavy crop and this is likely to occur as most soils have very low potassium levels. There is a striking response of such coffee trees to a heavy application of potassium fertilizer. Magnesium deficiency is most often caused by a relative potassium excess under the influence of a K/Mg antagonism. As K and Mg levels are low in the soils of Nchima, magnesium deficiency is not likely to occur. Potash application to the coffee crop may lead to magnesium deficiency. The quickest way to cure the deficiency is to spray three to seven times with a 1-2 % solution of Epsom salt at fortnightly intervals.

3 RBOOMMENDATIQNS As a new fertility survey will be conducted in October 1990, recommendations as given here are preliminary only. Detailed fertilizer recommendations in kg/block will be given after the new soil analysis has been carried out. This will be based on the availability of the different types of fertilizers in Malawi. 3.1 Tea - Urea is not a suitable fertilizer for tea at Nchima. At first it increases the soil acidity and secondly, as there is usually a surface mulch of leaf litter under the tea bush, a high percentage of nitrogen gets volatilized after application. Hence urea might be more expensive per kg N than NPK fertilizers.

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- On extremely acid soils (field 4, 10) one may consider erecting fertilizer trials with CAN in order to avoid the acidifying effect of using urea or SA. But this fertilizer should only be applied in combination with a potassium fertilizer. The calcium in the CAN gives rise to potassium deficiencies. - A compound fertilizer with a NPK ratio 25-5-5 or 20-10-10 is the most suitable fertilizer for the tea at Nchima Estate preferably given in split application after the onset of the rains. On soils with very low potash and phosphorus levels, 20-10-10 should be preferred. If no compound fertilizers are available, a combination of the following single fertilizers are recommended: CAN alternately used with SA, Muriate of Potash and di-^ammonium phosphate (or single, double or triple super phosphate). 3.2 Coffee - Based exclusively oh the soil analysis report of 1987, it can be concluded that there are only a very few sites (i.e. Kablll and KablllG) with a fair fertility for coffee cultivation. For most lands the soil fertility is affecting successful coffee cultivation. New coffee plantings are only recommended with an uplift of the soil fertility by means of liming, organic manuring and/or NPK fertilizing. - Liming to pH 5.0/5.5 on the extremely acid soils in order to improve the suitability for coffee cultivation is required. An application of 3-5 tons/ha of dolomitic limestone (containing Mg) every three year is recommended. The lime application induces unfavourable calcium/potassium ratios and it should be accompanied with muriate of potash applications. - For young coffee a N/P205/K20 ratio is preferred with the accent on P. e.g. a 1:2:1 ratio whereas for coffee in production an N/P205/K20 ratio of 2:1:2 is recommended. - For the existing coffee plantings fertilizing with hulls and pulp as a good source of potassium is recommended. In addition CAN may be used as a'N source. The fertilizer should be applied in a circle from 30 to 90 cm around young coffee or in a band about 60 to 90 cm wide between rows of mature coffee. Heavy dressings of pulp and hulls leads to magnesium deficiency symptoms and spraying with Epsom salts may be required.. - Urea and SA are unsuitable for fertilizing the.coffee at Nchima Estate. CAN is more suitable but it should not be applied without potash fertilizers. - Foliar analysis for existing coffee plantings» and soil analysis for new areas are the most appropriate ways to determine the nutrient* disorders and their cure.

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Annex 1 Analytical Data of Samples from 1987 field

block depth pH H20 Avail. P

4 4 4 6 6 6 7 7 10 10

4 9 15 5 7 13 2 5 6 9 chipatala 3 chipatala 5 chipatala 7 chipatala 10 chiwale 1 chiwale 3 malinga moy 1 malinga moy 3 nkolckosa 2 nkolokosa 6 peters 4 peters 7 v.p. tea 2 v.p. tea 5 no.l top no.l top no.2 no. 2 no.3 no.3 no.4 no.4 abraml abraml abram2 ahram2 chil chil no.l low no.l low nankh nankh nched nched

off off trott trott beat beat

tr. - traces

topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoi1 subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil

4.3 4.4 3.8 4.1 4.4 4.4 4.0 4.2 3.9 4.2 4.7 4.0 4.8 4.2 4.2 5.0 4.5 4.4 3.9 4.4 4.5 4.0 4.8 4.7 4.1 4.3 4.5 4.6 4.2 4.5 4.5 4.7 5.4 5.3 5.1 5.6 5.3 4.9 4.2 4.5 5.2 5.0 4.8 4.8 4.7 4.5 4.5 5.0 4.5 5.0

ppm

Been. Cations meq% Loss on Hg ign. % K Ca

25 5 41 3 32 2 130 10 37 1 10 2 2 18 8 5 14 1 3 6 48 137 18 5 52 14 41 7 5 14 tr. 3 19 2 15 2 5 tr. 3 5 3 tr. 2 tr. 22 2 6 tr. 3 tr.

0.09 0.20 0.20 0.18 0.30 0.16 0.11 0.14 0.11 0.23 0.31 0.33 0.35 0.16 0.11 0.03 0.16 0.32 0.22 0.13 0.12 0.28 0.29 0.30 0.25 0.16 0.27 0.20 0.25 0.20 0.53 0.37 0.55 0.40 0.55 0.52 0.69 0.35 0.25 0.30 0.47 0.24 0.49 0.28 0.21 0.20 0*43 0.37 0.47 0.40

0.23 0.28 0.25 0.15 0.28 0.23 0.33 0.23 0.20 0.19 0.33 0.23 0.40 0.20 0.18 0.43 0.43 0.28 0.28 0.19 0.28 0.26 0.23 0.35 0.58 0.19 0.26 0.36 0.20 0.34 0.36 0.50 0.60 0.45 0.49 0.49 0.77 0.43 0.24 0.45 0.44 0.41 0.41 0.37 0.19 0.29 0.37 0.52 0.30 0.52

0.06 0.10 0.04 0.04 0.08 0.07 0.05 0.04 0.01 0.14 0.26

o.u

0.32 0.03 0.04 0.16 0.08 0.09 0.06 0.09' 0.09 0.06 0.19 0.36 0.05 0.11 0.12 0.19 0.11 0.22 0.26 0.37 0.59 0.42 0.39 0.45 0.59 0.29 0.25 0.47 0.30 0.34 0.51 0.64 0.15 0.34 0.41 0.63 0.34 0.61

7.0 6.5 10.2

6.2 8.5 5.8 5.7 8.8 6.4 10.1

9.5 7.6 7.2 7.4 5.2 4.1 8.4 8.9 10.8

6.3 5.5 7.8 6.9 6.8 6.4 6.6 7.1 7.2 10.2 13.4 10.7 10.5 12.3 11.0

7.8 8.8 8.3 9.7 7.6 7.7 7.2 8.5 9.5 8.1 8.0 8.7 11.1 10.0

9.0 9.7

Annex 1 Analytical Data of Samples from 1987 (continued) field

block depth pH H20 Avail. P

ppm coff coff chip chip jull jull kabl kabl kabll kabll kablll kablll kabIII/85 kabIII/85 kablllG kablllG kad2 kad2

t22 t22 t25 t25 west west

topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil topsoil subsoil

5.2 4.9 4.6 5.1 4.8 5.1 5.3 5.8 5.2 5.3 -

5.5 5.5 4.8 4.9 5.4 5.5 4.6 4.8 4.8 5.0 4.3 4.8 4.5 5.0

25 8 5 tr. 6 tr. 15 tr. 1 tr. 1 tr. 7 tr. 3 2 52 27 29 2 15 2 28 1

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Exch. Cations meq% Loss on K Ca Mg ign. % 0.39 0.53 0.56 0.32 0.53 0.48 0.62 0.60 0.63 0.39 0.79 0.62 0.27 0.53 0.21 0.33 0.50 0.34 0.43 0.29 0.21 0.20 0.46 0.37

0.50 0.43 0.45 0.61 0.47 0.71 0.84 0.72 0.38 0.40 0.69 0.58 0.40 0.41 0.43 0.30 0.69 0.94 0.65 0.77 0.43 0.73 0.53 0.83

0.60 0.42 0.31 0.51 0.53 0.62 0.60 0.64 0.34 0.62 0.63 0.51 0.62 0.57 0.46 0.34 0.65 1.31 0.58 1.19 0.30 0.89 0.52 1.25

7.7 7.9 9.9 10.1

8.0 9.7 6.9 8.9 6.6 6.5 8.4 9.1 7.4 6.8 4.1 3.1 7.0 7.0 7.4 8.5 8.0 8.7 9.2 8.6

Annex 2 Keys to soil depth, soil reaction classes and general Ratings of Soil Fertility Parameters

thickness topsoil very thin thin mod. thick thick very thick

cm

thickness solum