To study the effects of four different levels of fertilizer NPK nutrients, applied at a ratio of N:P 2

Transcription

1 98 E4 Effect of different levels of fertilizer NPK nutrients on growth, yield and economic parameters of coffea arabica (V. catimor) grown on the ferralitic soils of entral ighlands, Vietnam Objective To study the effects of four different levels of fertilizer NPK nutrients, applied at a ratio of N:P 2 O = 2::2, on growth, yield and economic parameters of coffea arabica (V. catimor) grown on ferralitic soils derived from basalt in the entral ighlands of Vietnam. Background The variety atimor is known for its relatively high resistance to leaf rust (emileia varistatrix). offee trees in this experiment were planted in 99. Besides coffee yield (t green bean ha - ), plant growth parameters, incident of diseases, nutrient content in soil and plant and economic parameters were regularly measured in order to assess the effect of the four levels of fertilizer NPK application. Site details Location: This fertilizer experiment was conducted at the Western ighlands Agro- orestry Science & Technical Institute (WASI) in Buon Ma Thuot, Dak Lak Province. offee is grown at an altitude of 4 5 m above sea level. Soil type: erralitic soils derived from basalt. The well-structured and well-drained soil is of clayey texture and classified as a Rhodic erralsol in the AO-Unesco system. Soil characteristics (analyses of topsoil samples collected before the start of the experiment): p: Acidic (pkl = 4.4); Soil organic matter (SOM): Well-supplied of organic matter (4.5% SOM) Soil N: Medium reserves of N (Total N =.2%); Soil P: Medium reserves of P (Available P = 4 mg kg - ); Soil K: Medium reserves of K (Available K = 268 mg kg - ); ation exchange capacity (E): Medium levels of exchangeable a (3.4 cmol kg - ) and exchangeable Mg (3.85 cmol kg - ).

2 99 Temperature: Average air temperature ranges between 2 º (December) and 26 º (May). Rainfall: Average annual rainfall 7 8 mm; mostly received between May and November. A distinct dry season occurs between December and April; during this period coffee is irrigated 3 4 times using a total of 25 3 m 3 water drawn from wells. Materials and methods Experimental design: The experiment was initiated in 992 with treatments applied in a randomized complete block design with four replicates per treatment. offea arabica was planted at a density of 6,666 trees ha - without shade trees. ertilizer application (Table E3-): ertilizer nutrients were applied as urea (85% of N), AS (5% of N), MP (P 2 ) and MOP (K 2 O). our fertilizer NPK doses at a ratio of N: P 2 : K 2 O = 2::2. After the first harvest in 993, the levels of fertilizer NPK nutrient application were adjusted. offee trees were maintained at maximal height of.8 m. Weed, pest and disease control measures were applied as required. The following parameters were recorded two years after planting: Plant growth (plant height, tree trunk diameter, number of laterals, number of secondary laterals, length of longest lateral); Incidence of die-back disease (olletotrichum gloeosporioides); Leaf and soil nutrient content (soil nutrient content measured after five years); and Yield and economic returns. Results Effect of different levels of NPK on plant growth (igure E4-, Table E4-2): In 4 (the largest NPK rate throughout the experiment), plant growth parameters except length of longest lateral were >2% larger than those recorded in (the smallest NPK rate throughout the experiment). These results indicate that coffea arabica plants grow at a faster rate in treatments that receive larger fertilizer NPK nutrient rates. owever, no significant difference in vegetative measurements was observed between treatments.

3 Effect of different NPK levels on disease incidence (igures E4-2 and E4-3, Tables E4-3 to E4-5): In 4 (largest NPK rate), the number of coffee trees and branches infected with die-back disease (olletotrichum gloeosporioides) was significantly smaller than in (smallest NPK rate). This indicates that coffea arabica plants that receive larger NPK application rates have a lower incidence of die-back disease. Effect of different NPK levels on nutrient content in leaf (Table E4-4) and soil (Table E4-5, igure E4-3): Among all the nutrients N, P, K, a, Mg, and S contained in the fertilizer sources used, the larger fertilizer NPK nutrient supply apparently only increase leaf K. In 4, leaf K was measured at.76% compared with.48% in. Analysis of topsoil chemical properties five years on showed that the content of soil organic matter (SOM) had become smaller in all treatments when compared with the untreated topsoil at the start of the experiment. With increasing NPK rates applied in the treatments: available K in 4 increased to 37. mg kg - from 268. mg kg - before the experiment began, whilst exchangeable Mg decreased to.6 cmol kg - from 3.85 cmol kg - before the experiment began. Yield and economic returns (Table E4-6, igure E4-4): During the seven years of the experiment, annual yields of coffea arabica in six of these years were largest in 4 (the largest NPK rate). This was ~.4 t green beans more than in (smallest NPK rate). In 994 and 996, coffee yields of >5 t green bean ha - were recorded for 4. offee yields in 998 obviously were strongly affected by extreme dry conditions caused by the 997/98 southern weather oscillation. In 997 yields in 4 were ~2.9 t green bean ha - larger than in ; this may be attributed to better droughtresistance in plants due to the larger K supply in 4. Summary and conclusions Based on the observations in this experiment, the potential economic benefits can be substantial in spite of declining coffee prices during the period of experimentation in from Among the four NPK rates applied, the largest application rates (35 N + 75 P K 2 O kg ha - ) resulted in the largest net income (net returns over fertilizer cost) of US$ 3,688 ha -. When compared with the lowest level of fertilizer NPK nutrient supply tested, 4 (the largest NPK rate) resulted in ~US$,235 ha - yr - of additional net returns and the largest value:cost ratio (VR) of 5.54 (Table E4-7, igure E4-5). The results from this trial suggest strongly that proper cultivation of coffea arabica (V. atimor) can result in large yields of 4 5 t green bean ha - yr - over a period of seven

4 years in the Western ighlands of Vietnam. owever, in order to maintain such high yield levels, fertilizer NPK nutrients must be supplied in sufficient quantities and at a suitable N:P:K ratio (e.g. 35 N + 75 P K 2 O kg ha - yr - ). Table E4- s fertilizer NPK nutrient levels and rates. Application period 2 nd and 3 rd years after planting ( ) Production period (994-2) Rate of application N P 2 K 2 O Table E4-2 Effect of four fertilizer NPK nutrient levels (N:P 2 O=2::2) on the number and length of laterals, plant height, and trunk diameter of coffea arabica (v. atimor) two years after planting grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2) eight Trunk diameter No. of No. of secondary Length of longest (cm) (cm) laterals laterals lateral (cm) Table E4-3 Effect of four fertilizer NPK nutrient levels (N:P 2 O=2::2) on the incidence of die-back disease (olletotrichum gloeosporioides) of coffea arabica (v. atimor) grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2) Level of NPK Infected berries Infected trees Infected branches ( kg ha - ) (%) (%) (%) 7:85: a 2. 2 a 2 23:5: ab 8. ab 3 29:45: b 7. 4 ab 4 35:75: b 6. 8 b N.S.

5 2 Table E4-4 Effect of four fertilizer NPK nutrient levels (N:P 2 O=2::2) on leaf N, P, K, a, Mg, and S content of coffea arabica (v. atimor) two years after planting grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2) Level of NPK Leaf N Leaf P Leaf K Leaf a Leaf Mg ( kg ha - ) (%) (%) (%) (%) (%) 7:85: :5: :45: :75: Table E4-5 Levels of soil organic matter (OM), total N, available P (Avail. P), available K (Avail. K), exchangeable a (Exch. a) and exchangeable Mg (Exch. Mg) before and after application of four fertilizer NPK nutrient levels (N:P 2 O=2::2) over five years to coffea arabica (v. atimor) grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2) Level of NPK ( kg ha - ) p Kl OM N Total Avail. P % % mg kg Avail. K Exch. a Exch. Mg - mg kg - cmol k g- cmol k g - - Before experiment :85: :5: :45: :75: Table E4-6 Effect of four fertilizer NPK nutrient levels (N:P 2 O=2::2) on the annual green bean yield of coffea arabica (v. atimor) grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2) Level of NPK ( kg ha - ) Green bean yield (t ha - yr - ) Mean 7:85: b 3.87 b 3.5 b 3.9 b 2.7 c 2.6 c 3.4 b 3.5 c 2 23:5: a 4.89 a 3.2 b 3.2 b.88 c 2.27 c 3.64 b 3.36 c 3 29:45: a 5.3 a 4. a 4.94 a 3.22 b 2.59 b 3.73 ab 3.85 b 4 35:75: a 5.27 a 4.62 a 5.4 a 4.96 a 2.94 a 4.66 a 4.44 a

6 3 Number of laterals Longest lateral (cm) Plant height (cm) Trunk diameter (cm) :6:2* 3:5:3* 75 2:6:2* 3:5:3* 4 *N:P 2 O (kg ha - ) *N:P 2 O (kg ha - ) Number of laterals Trunk diameter (cm) Number of secondary laterals eight (cm) Longest lateral (cm) O (kg ha - ) igure E4- Effect of two fertilizer NPK nutrient application levels (N:P 2 O=2::2) on the number and length of laterals, plant height, and trunk diameter of coffea robusta grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2) Rate of infection (%) :6:2* 3:5:3* *N:P O K O (kg ha - ) 2 5: 2 Trees Branches Leaf P (%) Leaf N, Leaf K (%) :6:2* 3:5:3* *N:P O :K O (kg ha - ) Leaf P Leaf N Berries Leaf K O (kg ha - ) igure E4-2 Effect of two fertilizer NPK nutrient application levels (N:P 2 O=2::2) on the incidence of die-back disease (olletrotrichum gloeosporioides) and leaf N, P, and K content of coffea robusta grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2)

7 4 SOM, exchangeable a, exchangeable Mg (cmol kg - ) Total N (%) SOM Exch. Mg Exch. a Before expt. 7:85:7* 23:5:23* 29:45:29* 3:5:3* Total N Available P (mg kg - ) Available K (mg kg - ) Avail. P Avail. K Before expt. 7:85:7* 23:5:23* 29:45:29* 3:5:3* O (kg ha - ) igure E4-3 Levels of soil organic matter (OM), total N,, exchangeable a (Exch. a), exchangeable Mg (Exch. Mg), available P (Avail. P), and available K (Avail. K) before and after application of four fertilizer NPK nutrient levels (N:P 2 O=2::2) over five years to coffea arabica (v. atimor) grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2)

8 5 Green bean yield (t ha - ) :75:35* 29:45:29* 23:5:23* 7:85:7* O (kg ha - ) igure E4-4 Effect of four fertilizer NPK nutrient levels (N:P 2 O=2::2) on the annual green bean yield of coffea arabica (v. atimor) grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2) Green bean yield (t ha - ) US$ ha :85:7* 23:5:23* 29:45:29* 35:75:35* Green bean yield Return ost O (kg ha - ) igure E4-5 Effect of four fertilizer NPK nutrient levels (N:P 2 O=2::2) on average green bean yield, cost of fertilizer application, and economic returns of coffea arabica (v. atimor) grown on a Rhodic erralsol derived from basalt in Buon Ma Thuot, Dak Lak Province in Vietnam. (Ton Nu Tuan Nam et al., 2)