size is 5 ha in these regions and coffee farming is quite devoid of fertilization due to
poor subsistence of farmers [147]. These farmers only use organic fertilizers, e.g.,
animal or poultry manure for fertilization and manual weeding for plant protection.
This is the most acceptable reason of yield reduction in east and central African
countries where up to 70% record yield drop was documented in last three decades.
The soils of these fields found quite low in N, Ca, and Mg near the critical value and
P above the critical level as these organic fertilizations are unable to supply the
required amount of these core nutrients. Soil, soil fertility, and fertilization are the
challenging factors to carry over with its direct or indirect influences not only on
coffee productivity but also on beverage quality as world’s best coffee farming
system are said to be at high altitudes with sloppy fields. These sloppy fields at
high altitude are also the center of high natural runoff and minerals leaching losses
collectively called soil erosion which broaden the importance of farm management
practices here [148–150]. The organic matter (OM) in the top crust (30 cm) of soil is
the first hit of this soil erosion where most of the feeder roots are located, which
means direct and immediate influence on the nutritional status of coffee tree. The soil
crust must consist of 80% OM and the amount of soil OM contents depends on
various ecological factors like intercropping, type of intercropped crop, absence or
presence of shading plants, pruning, pruning extent, plant density, weeding, rainfall,
wind, runoff, etc. Soil OM contents have a positive association with soil N, P
contents, and pH, whereas OM contents of agroforestry or intercropped systems
are always higher than the mono-crop system. In the mono-crop systems, OM
contents of Robusta fields found to be higher than that of the coffee Arabica fields
[135] and the reason behind these findings is the difference in the height of
cultivation of both crops as coffee Arabica always planted at higher elevation
where there is greater runoff and leaching affects as compared to lower altitudes.
On the other hand, in the intercropped or agroforestry systems, coffee Arabica tends
to store more OM contents than Coffee Robusta fields [135]. The fall in the level of
OM contents leads to compactness of surface soil affecting the root growth, lessens
the aeration, soil pH, soil porosity, soil water retention capacity, availability, and
recycling of nutrients, enhances the leaching of nutrients, and makes the plant more
vulnerable to insect pest and diseases. The lowering of pH is the most devastating
outcome of lower soil OM contents, which in turn affects the nutrients uptake by
plant, nutrients assimilation, OM mineralization, and microfaunal (microbes and
friendly insects or worms) activities. Mulching is highly recommended by several
authors in order to conserve the OM level of soil and increase the soil minerals
contents too [151–153]. N, K, Ca, P, and Mg are the basic required crop nutrients
which also showed a rise in level due to act of mulching. In addition to these cat ions,
OM is also important for incrementing the cationic exchange capacity (CEC) of
soils, which in turn improves physical characteristics, soil microorganism diversity,
and soil water relationship [147]. The choice of organic material for mulching
depends upon the several factors like availability, cost, season, ease of handling
and transportation, land, soil type, etc. Owing to biological nitrogen fixation features, leguminous crops are considered best for mulching irrespective of the fact of
their competition with main crop and lowering the soil pH due to N mineralization
27 “Coffee Bean-Related” Agroecological Factors Affecting the Coffee
667
poor subsistence of farmers [147]. These farmers only use organic fertilizers, e.g.,
animal or poultry manure for fertilization and manual weeding for plant protection.
This is the most acceptable reason of yield reduction in east and central African
countries where up to 70% record yield drop was documented in last three decades.
The soils of these fields found quite low in N, Ca, and Mg near the critical value and
P above the critical level as these organic fertilizations are unable to supply the
required amount of these core nutrients. Soil, soil fertility, and fertilization are the
challenging factors to carry over with its direct or indirect influences not only on
coffee productivity but also on beverage quality as world’s best coffee farming
system are said to be at high altitudes with sloppy fields. These sloppy fields at
high altitude are also the center of high natural runoff and minerals leaching losses
collectively called soil erosion which broaden the importance of farm management
practices here [148–150]. The organic matter (OM) in the top crust (30 cm) of soil is
the first hit of this soil erosion where most of the feeder roots are located, which
means direct and immediate influence on the nutritional status of coffee tree. The soil
crust must consist of 80% OM and the amount of soil OM contents depends on
various ecological factors like intercropping, type of intercropped crop, absence or
presence of shading plants, pruning, pruning extent, plant density, weeding, rainfall,
wind, runoff, etc. Soil OM contents have a positive association with soil N, P
contents, and pH, whereas OM contents of agroforestry or intercropped systems
are always higher than the mono-crop system. In the mono-crop systems, OM
contents of Robusta fields found to be higher than that of the coffee Arabica fields
[135] and the reason behind these findings is the difference in the height of
cultivation of both crops as coffee Arabica always planted at higher elevation
where there is greater runoff and leaching affects as compared to lower altitudes.
On the other hand, in the intercropped or agroforestry systems, coffee Arabica tends
to store more OM contents than Coffee Robusta fields [135]. The fall in the level of
OM contents leads to compactness of surface soil affecting the root growth, lessens
the aeration, soil pH, soil porosity, soil water retention capacity, availability, and
recycling of nutrients, enhances the leaching of nutrients, and makes the plant more
vulnerable to insect pest and diseases. The lowering of pH is the most devastating
outcome of lower soil OM contents, which in turn affects the nutrients uptake by
plant, nutrients assimilation, OM mineralization, and microfaunal (microbes and
friendly insects or worms) activities. Mulching is highly recommended by several
authors in order to conserve the OM level of soil and increase the soil minerals
contents too [151–153]. N, K, Ca, P, and Mg are the basic required crop nutrients
which also showed a rise in level due to act of mulching. In addition to these cat ions,
OM is also important for incrementing the cationic exchange capacity (CEC) of
soils, which in turn improves physical characteristics, soil microorganism diversity,
and soil water relationship [147]. The choice of organic material for mulching
depends upon the several factors like availability, cost, season, ease of handling
and transportation, land, soil type, etc. Owing to biological nitrogen fixation features, leguminous crops are considered best for mulching irrespective of the fact of
their competition with main crop and lowering the soil pH due to N mineralization
27 “Coffee Bean-Related” Agroecological Factors Affecting the Coffee
667