Mono Potassium Phosphate ( PeaK ) foliar application for Rice in the Red River Delta of Vietnam

Mono Potassium Phosphate ( PeaK ) foliar application for Rice in the Red River Delta of Vietnam Tran Thuc Son*, Nguyen Van Chien*, Yossi Ankorion** Abstract Root nutrition is the main method for rice fertilization in RRD, but foliar fertilizer application may add very positive yield effect. Recent research on PeaK Sprays to supply P and K through rice leaves not only increased rice yield on poor total K soil (Degraded) but also on rich total K soil (Alluvial) in this area. So farmers in this region have started using Peak as an additional supply of these nutrients to rice. 1. Introduction Red River Delta (RRD) is the one of the most intensive agricultural regions in Viet Nam. Rice is the most important crop in RRD. Every year it provides for the country about 6.0 millions tones of paddy. For many years, farmer in this area have used new high yield potential rice varieties such as: TG4, TG5, Q5, Khangdan with high demand of nutrition. There are many poor nutrition areas growing rice in the RRD like Acrisol, characterized with low CEC (4.5-7.8 me/100 g. soil), clay content and total soil P and K as well as their available forms. The need of macronutrient in general and P, K in particular for crops is great. We assume that root fertilization could not be adequate for rice, so foliar application may play additional effect for attaining high yield and good quality of rice. *National Institute for Soils and Fertilizers (NISF),Vietnam **Rotem Amfert Negev Ltd,Israel 1

2. Methodology and Content 2.1. PeaK testing steps To study the effect of PeaK on rice, the following steps were carried out: (1). Study the effects of PeaK rate and timing for Spring and Summer rice (on station trials). (2). Study the most effective treatments on Farmer Fields(on farm stage) 2.2. The experiments and trials were done: (1). The effect of PeaK to Spring Rice on Degraded and s (2). The effect of PeaK to Summer Rice on Degraded and s (3). On farm research of Peak effect to Spring Rice on both soils (4). On farm research of Peak effect to Summer Rice on both soils 2.3. Location and Soil properties - : Hien Ninh Village, Soc Son District, Hanoi; ph= 4.5, CEC = 5.5 cmol/ kg soil, Total Soil K = 0.2%, Exchange K= 0.07 cmol/ kg soil, Total Soil P = 0.04%, P (Olsen)= 3.5 mg/kg - Red River : Thuong Mo Village, Dan Phuong District, Hatay Province; ph=5.3, CEC= 11.5 cmol/kg, Total Soil K= 2.2%, Exchange K= 0.19 cmol/kg, Total Soil P= 0.12%, P (Olsen)= 7.3 mg/kg 2.4. Rate and timing of fertilizer application for experiment For ; Spring rice: 10 tones FYM/ha at basal, 120 N/ha (20 % basal, 40 % first split at tillering, 40% at PI), 90 kg P 2 O 5 as basal, 90 K 2 O (50% at basal and 50 % at PI). Summer rice: 10 tones FYM/ha at basal, 90 kg P 2 O 5 as basal, 80 N/ha (20 % basal, 40 % first split at tillering, 40% at PI) and 60 K 2 O (50% at basal and 50 % at PI). For Red River ; Spring rice: 10 tones FYM/ha at basal, 150 kg N/ha (20 % basal, 40 % first split at tillering, 40% at PI), 60 kg P 2 O 5 as basal, 60 kg K 2 O (50% at basal and 50 % at PI). 2

Summer rice: 10 tones FYM/ha at basal; 60 kg P 2 O 5 as basal ; 100 kg N/ha (20 % basal, 40 % first split at tillering, 40% at PI)kg/ha; 30 kg K 2 O (50% at basal and 50 % at PI). 2.5. Lay Out of experiment: For experiment RCBD, with 4 replications, plot area 24 m 2 on and 20 m 2 on. 2.6. Treatments for experiment* (on station trials) Treat Concentration First Second PeaK spray spray kg/ha Notice T1 0.5% PeaK MT PI 10 MT: maximum tillering T2 1.0% PeaK MT PI 20 PI: panicle initiation T3 0.5% PeaK PI BH 10 BH: before heading T4 1% PeaK PI BH 20 T5 1% PeaK PI 10 T6 0.5% PeaK 0.5% ULB MT PI 10 N:P:K=1:1:1 T7 0.5% PeaK MT PI 15 3 rd spray at BH T8 1.0% PeaK MT PI 22 Seedling spray 5 days before transplanting** T9 Control Water spray T10 1% PeaK Double spray at 3 days 2 kg PeaK seedling spray interval - **At T8 and T10: 1 ha of rice nursery supplies 5 ha transplanting field, then total amount of PeaK sprayed at this stage = 10 kg: 5= 2 kg. 2.7 Spray method It is double spraying at 3-7 days interval with 500 l/ha (it means 2 sprays for each growth stage, for exam. at T1, PeaK is sprayed at MT stage at 0.5 % in 2 times with interval of 5 days, so the amount of PeaK sprayed at MT should be 500l x 0.5/100 x 2 times= 5 kg, then the total amount PeaK sprayed for T1 at MT and PI is 10 kg). 2.8. Rice variety of experiment: For spring rice DT 10 on Degraded and Khang Dan on ; for summer rice Khang Dan on and Q 5 on. 3

2.9. Location, soil, rice variety and fertilizer of on farm research On Degraded soil, on farm research was conducted on 4 farmers fields in Hien Ninh Village, Soc son District, Hanoi, with Hybrid, Khang Dan variety. On Alluvial soil it was conducted on 4 farmers fields in Dan Phuong Village, Dan Phuong District, Ha Tay Province with Q5 variety 4 treatments, each one is replicated in 4 householders. Plot area is 200-300 m 2. Treatment Spray I** Spray II** Total PeaK (Kg/ha) 1. FFP*** Water spray Water spray --- 2. FFP+ 1% PeaK Seedling stage 2* 3. FFP+ 1% PeaK PI 10 4. FFP+ 1% PeaK Seedling stage PI 12 * For 1 ha transplanting,**double spray at 5-7 days interval, *** Farmer Fertilizer Practices 3. Results and Discussion 3.1. Experiments 3.1.1. The effect of PeaK on Spring rice In, PeaK spray increased 18-54 panicles/ m 2, decreased unfilled grain rate. Grain yield in average is 400 kg grain increase or 8.8 % for all PeaK spray treatments over control and varied from 180-550 kg/ ha, the best treatments (T3, T8, T10) added more than 500 kg paddy/ ha or 12 % increase (table 1). In (table 2), PeaK spray increased 9-32 panicles/ m 2, decreased unfilled grain rate, slightly increased grain number/ panicle. Increase of grain yield in average is 547 kg/ha or 9.5 % for all PeaK spayed treatments over control and varied from 280-930 kg/ ha. Additional 790-930 kg/ ha (13-15 %) could be achieved at the best treatments (T2 and T8). 4

Table 1. The effect of PeaK on yield and yield components of Rice in Degraded soil Treatment Panicle/ Unfilled grain rate Grain yield Yield increase m 2 % Kg/ ha Kg/ ha % T1 355 15.3 4840* 280 6.1 T2 387 16.5 4930** 370 8.1 T3 382 16.5 5100** 540 11.8 T4 374 16.2 4920** 360 7.9 T5 355 15.0 5000** 440 9.6 T6 360 15.6 4880* 320 7.0 T7 360 15.7 4740ns 180 3.9 T8 369 14.9 5110** 550 12.1 T9 333 16.8 4560 0 0.0 T10 351 13.3 5100** 540 11.8 CV =3.1 %; LSD (5%)= 253; LSD (1%)= 342 Data from table 3 showed that at the PI stage, total plant NPK uptake of PeaK sprayed treatments at seedling stage and MT was higher than that of control (T9) on degraded soil. The highest N uptake was seen when PeaK was sprayed 3 times at seedling, MT and PI stages (T8).The same tendency was observed on alluvial soil. 5

Table 2. The effect of PeaK on yield and yield components of Rice in Alluvial soil Treat. No of panicle/m 2 No spikelet Unfilled grain rate % Grain yield Kg/ ha Yield increase /panicle kg/ha % T1 356 98 10.0 6330* 310 5.1 T2 356 105 8.2 6810** 790 13.1 T3 374 97 10.6 6300* 280 4.7 T4 360 99 8.3 6540** 520 8.6 T5 360 100 8.5 6640** 620 10.3 T6 360 98 10.3 6390** 370 6.1 T7 351 101 8.4 6460** 440 7.3 T8 374 102 7.6 6950** 930 15.4 T9 342 97 12.8 6020 0 0.0 T10 356 102 8.2 6680** 660 11.0 CV =2.8 %; LSD (5%)= 269; LSD (1%)= 363 Table 3. The effect of PeaK on NPK uptake at PI stage on and Treat., kg/ha N P 2 O 5 K 2 O N P 2 O 5 K 2 O T1 127.5 6.6 61.1 106.2 8.9 46.2 T2 125.8 7.1 65.8 95.2 7.2 45.3 T6 98.4 7.7 70.3 122.6 7.3 39.4 T7 116.4 6.9 63.2 123.9 8.2 42.0 T8 138.9 8.8 63.0 132.8 9.1 44.8 T9 91.8 5.8 53.9 73.5 6.0 38.4 T10 116.7 7.2 63.6 116.2 9.8 51.5 6

NPK uptake at harvesting period of PeaK treated treatments was higher than that of control (T9) in both Degraded and s. N uptake was increased from 9.5 (T7) to 30.9 % (T8) in and 15 % (T1) and 28 % (T8) in. The Highest N uptake was observed when PeaK sprayed 3 times at seedling, MT and PI stages in Both Soils, P and K uptake of this treatment was also significantly higher than control ones (table 4). Table 4. The effect of PeaK on NPK uptake at harvest on and Alluvial Treat. Soil, % of control N P 2 O 5 K 2 O N P 2 O 5 K 2 O T1 111.4 145.6 137.1 115.0 110.6 123.4 T2 112.6 144.2 124.9 118.5 103.1 118.4 T3 115.1 187.1 142.9 117.9 127.3 110.9 T4 118.3 153.1 127.7 126.1 99.6 121.1 T5 128.2 174.1 121.2 124.9 115.0 126.7 T6 117.7 175.5 120.7 118.8 116.3 117.9 T7 109.5 184.4 111.8 117.2 104.8 116.3 T8 130.9 142.2 120.2 128.1 119.8 117.5 T9 100.0 100.0 100.0 100.0 100.0 100.0 T10 122.5 149.7 119.1 117.6 125.6 120.0 Based on VCR value (table 5), economical effect of PeaK for Spring Rice on could be arranged as following: T10 > T3 > T5 > T6 > T1 > T8 > T2 > T4 > T7. and this on would be: T10 > T5 > T8 > T2 > T6 > T1 > T7 > T3 > T4 But, in, Highest income and benefit is treatment sprayed PeaK 3 times at seedling, MT and PI stages (T8). 7

Table 5. The economical effect of PeaK to spring rice on and Alluvial Soil Treat. Additional Additional income VCR** income VCR** 1000 VND/ha 1000 VND/ha T1 560 2.67 620 2.95 T2 740 1.76 1580 3.76 T3 1080 5.14 560 2.67 T4 720 1.71 1040 2.48 T5 880 4.19 1240 5.90 T6* 640 2.78 740 3.22 T7 360 1.14 880 2.79 T8 1100 2.38 1860 4.03 T9 - - - - T10 1080 25.71 1320 31.43 Price of 1 kg rice: 2000 VND, of 1 kg of PeaK: 21000 VND * including cost of 0.5 % ULB,** not including labor cost 3.1.2. The effect of PeaK on Summer Rice On Degraded soil, treatments sprayed with PeaK had tendency to increase panicles/m 2, the highest increase belonged to T4 with an increase of 29 panicles/m 2. The unfilled spikelet rate was also decreased. Paddy yield was increased with an average of 550 kg/ha and varied from 370 kg (T3) to 960 kg (T6), the best treatments (T6, T7) added 710-960 kg paddy/ ha or 14-18 % increase (table 6 and 7). The same picture was seen on Alluvial soil (table 6 and 7), number of panicle was also increased from 18 (T3) to 36 T4)/ m 2, the unfilled spikelet rate was decreased. Paddy yield was increased with an average 560 kg/ ha and varied from 370-830 kg/ ha. The additional yield of 730-830 kg/ha or 11.9-13.5 % were seen at the best treatments (T2 and T8). 8

Table 6. The effect of PeaK on yield component of summer Rice Treat. Panicle/m 2 Unfilled grain rate % Degraded Alluvial Degraded Alluvial T1 356 305 11.8 14.3 T2 340 310 12.9 13.1 T3 353 303 12.0 13.9 T4 384 321 12.0 13.7 T5 368 320 9.5 13.0 T6 380 309 12.6 14.0 T7 368 312 12.3 15.5 T8 362 318 12.1 14.1 T9 355 285 13.6 15.9 T10 355 310 12.2 15.7 Table 7. The effect of PeaK on yield of summer Rice Treat. Degraded Alluvial Grain yield Yield increase Grain yield Yield increase Kg/ ha Kg/ ha % Kg/ ha Kg/ ha % T1 5630** 420 8.1 6590** 450 7.3 T2 5640** 430 8.3 6870** 730 11.9 T3 5580** 370 7.1 6510** 370 6.0 T4 5790** 580 11.1 6720** 580 9.4 T5 5800** 590 11.3 6700** 560 9.1 T6 6170** 960 18.4 6690** 550 9.0 T7 5920** 710 13.6 6560** 420 6.8 T8 5710** 500 9.6 6970** 830 13.5 T9 5210 0 0 6140 0 0 T10 5640** 430 8.3 6660** 520 8.5 Sp: CV =3.1 %; LSD (1%)= 342, Sum: CV =2.8 %, LSD (1%)= 363 The NPK uptake at PI stage on degraded soil of PeaK sprayed treatment at seedling period and MT was significantly higher than that of control (T9), effect of PeaK spray was the same on alluvial soil (table 8). Results of table 9 show that on degraded soil, N uptake of rice was increased from 4.6 % (T10) to 11.8 % (T5), K uptake increased from 7.7 % (T5) to 26% (T3) over control (T9). On Alluvial soil, all nutrient uptake of summer rice was increased. 9

N uptake of rice was increased from 6.4 % (T7) to 29.7 % (T5), P uptake increased from 3.5 % (T3) to 70.9% (T2) and K uptake increased from 8.1 % (T7) to 40.5 % (T4) over control (T9). Table 8. The effect of PeaK on NPK uptake at PI stage on and, kg/ha Treat. N P 2 O 5 K 2 O N P 2 O 5 K 2 O T1 88.6 6.4 105.2 76.4 4.1 47.2 T2 84.5 5.4 104.0 72.1 3.9 42.4 T6 85.5 4.9 112.3 78.0 4.1 42.9 T7 90.0 4.9 102.3 71.7 3.6 41.6 T8 89.7 8.0 108.2 75.4 3.7 38.3 T9 75.7 4.4 84.1 64.4 3.4 34.7 T10 95.8 5.7 113.3 81.9 4.5 45.3 Table 9. The effect of PeaK on NPK uptake at harvest on and Alluvial Treat. Soil, % of control N P 2 O 5 K 2 O N P 2 O 5 K 2 O T1 104.8 96.6 110.0 108.0 127.9 132.8 T2 105.0 98.9 112.1 115.9 170.9 113.0 T3 105.0 102.2 126.0 119.6 103.5 115.3 T4 107.4 98.9 114.3 126.0 126.7 140.5 T5 111.8 105.6 107.7 129.7 161.6 110.5 T6 109.4 115.7 111.0 108.1 122.1 117.1 T7 106.6 103.4 117.8 106.4 159.3 108.1 T8 107.1 100.0 123.4 114.9 130.2 118.5 T9 100.0 100.0 100.0 100.0 100.0 100.0 T10 104.6 102.2 107.8 112.9 146.5 113.6 Based on VCR value (table 10), the most economical effect of PeaK on is the method of PeaK spray for seedling with the concentration of 10

1%, 2 times double spray at 3 day interval (T10). The economical effect of PeaK spray treatments could be arranged as follow: T10 > T6 > T5 > T7 > T1 > T3 > T4 > T8> T2 The economical effect of PeaK spray treatments on alluvial soil could be arranged as follow: T10 > T5 > T6 > T1 > T8 > T3 > T2 > T4 > T7 PeaK spray for seedling with the concentration of 1%, 2 times double spray at 3 day interval (T10) is also the most economically effective. Table 10. The economical effect of PeaK to summer Rice on and Treat. Additional Additional income VCR** income VCR** 1000 VND/ha 1000 VND/ha T1 840 4.0 900 4.3 T2 860 2.0 1460 3.5 T3 740 3.5 740 3.5 T4 1160 2.8 1160 2.8 T5 1180 5.6 1120 5.3 T6* 1920 8.5 1100 4.8 T7 1420 4.5 840 2.7 T8 1000 2.2 1660 3.6 T9 - - - - T10 860 20.5 1040 24.8 Price of 1 kg rice: 2000 VND, of 1 kg of PeaK: 21000 VND * including cost of 0.5 % ULB,** not including labor cost 3.1.3. Assessment (a). PeaK sprays at concentration of 0.5% -1%, 500 l/ ha, could increase grain yield of spring rice on degraded soil 280-550 kg/ha, on Alluvial soil 280-930 kg/ ha and of summer rice on degraded soil 420-960 kg/ha, on alluvial soil 370-830 kg/ha.(the higher figures refer to the optimal treatments screened at this research work). 11

(b). Total NPK uptake of PeaK spraying treatments is higher than that of non-peak spray. (c).the economical effect of PeaK spray at seedling stage with 1% concentration, 2 times double spray, 10 days before transplanting is highest. In this case, 1 VND input can attains 31.4 VND on alluvial soil and 25.7 VND on degraded soil in spring rice and 24.8 VND on Alluvial soil and 20.5 VND on degraded soil. 3.2. On farm research of the most effective treatments The above assessment showed that the high economic effect of PeaK foliar was double spray at seedling in interval of 3 5 days and 10 days before transplanting with conc. 1%, 500 l/ha. PeaK spray at PI with conc. 1%, 500l/ ha also gave high economical effect (in 1999). So in 2000 we use these 2 treatments in all trial sites in both degraded and alluvial soil. Table 11. The effect of PeaK sprayer on rice yield in degraded soil and alluvial soil Treat Spring rice, kg/ ha Summer rice, kg/ ha Degraded Alluvial Degraded Alluvial T1 5830 7000 4890 6070 T2 6290 7540 5220 6450 T3 6560 7540 5440 6600 T4 6780 7900 5460 6760 Average of 4 replications Data from table 11 and figure 1 and 2 showed that PeaK sprayed treatments in spring crop rice could increase rice yield from 460 kg/ ha or 7.9 % (T2) to 950 kg/ ha or 16.3 % (T4) on degraded soil and from 540 kg/ha (T2, T3) to 900 kg/ ha (T4) on alluvial soil. In summer crop, the increase of PeaK sprayed ones was from 330 kg to 570 kg paddy/ ha on degraded soil and 380 kg to 690 kg/ ha. The economical effect of PeaK was highest when spraying at seedling stage for Spring rice and summer rice for both soils (with highest VCR). But the highest yield 12

and income belonged to treatment spraying PeaK at seedling stage and PI stage (table 12). Table 12. Economical efficiency of PeaK for Rice Spring crop Summer crop Treat. Degraded Alluvial Degraded Alluvial Additional output* VCR Additional output* VCR Additional output* VCR Additional output* VCR T1 T2 920 21.90 1080 25.71 720 17.14 684 16.29 T3 1460 6.95 1080 5.14 900 4.29 972 4.63 T4 1900 7.54 1800 7.14 972 3.86 1206 4.79 * 1000 VND/ ha; Price of 1 kg rice: 2000 VND, of 1 kg of PeaK: 21000 VND Figure 1. The effect of PeaK spray to Spring Rice on Degraded and % 140 120 100 80 60 40 20 0 The Effect of PeaK to Spring Rice No PeaK PeaK spray at SL PeaK spray at PI Soil type 13

Figure 2. The effect of PeaK spray to Summer Rice on Degraded and % 140 120 100 80 60 40 20 0 The Effect of PeaK to Summer Rice No PeaK PeaK spray at SL PeaK spray at PI PeaK spray at both stages Soil type 4. Conclusions 4.1. In experimental as well as in on farm research, PeaK sprays at seedling stage before transplanting 5-10 days, PI stage or both 2 stages with conc. 1% (500 l/ ha) increased rice yield significantly in spring and summer crops in both soil types. 4.2. VCR index was highest at PeaK spray at seedling stage 4.3. PeaK spray at both 2 stages showed highest yield and income. 4.4. Farmers participated in on farm research and farmers attended to field meeting for assessment of the effect of PeaK foliar on rice crop admitted positive effect of PeaK. Hanoi, March 28,2002 14