Updating Nutrient Requirements for Rice-Based Cropping Systems in Non-Saline Tidal Flood Ecosystem of Bangladesh

Subject Areas : Research On Crop Ecophysiology

P. K.  SAHA ¹ (Ex-Chief Scientific Officer, Soil Science Division, BRRI, Gazipur-1701, Bangladesh)
M. N.  ISLAM ² (Scientific Officer, Soil Science Division, BRRI, Gazipur-1701, Bangladesh)
M. S.  ISLAM ³ (Agricultural Extension Officer, DAE, Bangladesh)

Received: 2017-10-17 Accepted : 2017-10-17 Published : 2016-01-01

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Original Research

Research on Crop Ecophysiology                Vol.11/1  , Issue 1  (2016), Pages: 28 - 34

 

 

Updating Nutrient Requirements for Rice-Based Cropping Systems in Non-Saline Tidal Flood Ecosystem of Bangladesh

 

P. K. Saha1, M. N. Islam2* And M. S. Islam3

1-Ex-Chief Scientific Officer, Soil Science Division, BRRI, Gazipur-1701, Bangladesh

2- Scientific Officer, Soil Science Division, BRRI, Gazipur-1701, Bangladesh

3-Agricultural Extension Officer, DAE, Bangladesh

 

*Corresponding author email: [e-mail]

 

 

 

Received:12 May 2015                                                                           Accepted: 5 September 2015 

 

 

Abstract

A number of crop problems can be related to inefficient management of nutrients and nutrient imbalances in the field. Appropriate fertilizer application is an important management practice to improve soil fertility and increase rice yield. Fertilizer should be applied based on a soil test and the desired yield. An experiment was conducted for four consecutive seasons: Boro (dry season) 2011-12 and Transplanted Aman (T. Aman, wet season) 2012 at the farmer’s field in Babuganj, Barisal (22.76˚ N and 90.30˚ E) to identify appropriate fertilizer management package for rice-based cropping systems in coastal non-saline tidal flood ecosystem in Bangladesh. In the present study, we examined the effects of eight fertilization treatments laid out in randomized complete block design with three replications. The treatment combinations were: T1 = 100% NPKSZn (STB), T2 = T1+25% N, T3 = T1+25% NP, T4 = T1+25% NK, T5 = T1+25% PK, T6 = T1+25% NPK, T7 = 75% of T1 and T8 = Absolute control. Results showed that application of different fertilizers significantly affected the grain yield at both of the seasons. In dry season, the highest grain yield was found in treatment T1 (100% STB) while T2 (T1+25% N) gave the highest grain yield in wet season. On the basis of yield performance, nutrient absorption and agronomic efficiency, it can be recommended that present fertilizer recommendation for dry season is enough while 25% additional N might be beneficial for wet season.

 

Keywords: AEZ-13, Cropping system, Nutrient uptake, Agronomic efficiency

 

Introduction

 

Bangladesh is one of the densely populated countries of the world. The total area of Bangladesh is 147, 570 km2. The non-saline tidal flood ecosystem of Bangladesh covers about 1.9 million hectares and the average yield of rice under non-saline tidal flood ecosystem is not more than 3.0 t ha-1 due to lack of technologies on appropriate fertilizer management packages, one of the major reasons (Saha et al., 2016).

Increased pressure of growing population demand more food. Thus it has become increasingly important to explore the possibilities of increasing the potential of these (non-saline tidal) lands for increased production of crops. To meet the food grain requirement for a growing population with limited land resources, an increasing pressure on the land is taking place without adequate compensation of the plant nutrient taken up from the soil. Nutrient mining is one of the major causes for stagnation or decline in yield of major crops of Bangladesh. If this problem of nutrient depletion is not corrected it will cause a serious damage of the soil and to the welfare of mankind. Relatively higher amount of fertilizers need to be used in high yielding varieties of different crop cultivation. Fageria et al. (1991) stated that supplying of mineral nutrients to crops in adequate amounts is one of the most important factors in achieving higher productivity. Fertilizer has now become a very costly commodity of agriculture in Bangladesh. A huge amount of foreign currency is needed to import different fertilizers in the country. It is, therefore, urgently needed to develop fertilizer management packages in such a way that it suited farmers’ resource constraints for ensuring the high use efficiency of fertilizers. Although Bangladesh Agricultural Research Consul (BARC) prepared fertilizer recommendation guide to adopt balanced fertilization for sustaining crop production in the country, farmers are getting extra benefit by additional fertilizer application. Therefore, we attempted to update the fertilizer requirements for rice-fallow-rice and rice-based cropping systems in non-saline tidal flood ecosystem under agro-ecological zone number 13 (AEZ 13).

 

Materials and methods

 

Experimental sites and seasons

 

The experiment was carried out for four consecutive seasons: Boro (dry season) 2011-12 and Transplanted Aman (T. Aman, wet season) 2012 at the farmer’s field in Babuganj, Barisal (22.76˚ N and 90.30˚ E). Two rice crops were grown annually in two seasons known as T. Aman and Boro. T. Aman was the wet season (June–July to November–December) in which transplanted rice was grown under partially irrigated conditions in the study area. Boro was the dry season (December–January to April–May) in which transplanted rice was grown under fully irrigated conditions. Semi-dwarf, high-yielding rice varieties were grown in the study area; BRRI dhan29 with 165 days growth duration was grown in dry season (2011-12), and local inbreed variety (Sada mota) with 215 days growth duration was grown in wet season. The field belongs to agro-ecological zone (AEZ) number 13 known as Ganges Tidal Floodplain (Mahmud et al., 2016). The silt clay loam soil having pH 6.84, organic carbon 1.04%, total N 0.10%, available P 17.4 mg kg-1, available K 0.17 cmol kg-1, available S 19.9 mg kg-1 and available Zn 1.5 mg kg-1 was used in the experiment. 

 

Experimental design and treatments

 

The experiment was established in farmer’s fields in a randomized complete block design with three replications. Treatments consisted of options for managing fertilizers in rice of non-saline tidal flood ecosystem. There were eight treatments in total: T1 = 100 % NPKSZn (Soil Test Basis, STB, according to the BARC, 2005); T2 = T1 + 25 % N; T3 = T1 + 25 % NP; T4 = T1 + 25 % NK; T5 = T1 + 25 % PK; T6 = T1 + 25 % NPK; T7 = 75 % of T1 and T8 = Absolute control (no fertilizer). In dry season, NPKSZn were applied at 162-11-58-11-0, 203-11-58-11-0, 203-14-58-11-0, 203-11-73-11-0, 162-14-73-11-0, 203-14-73-11-0, 122-8-44-8-0 and 0-0-0-0-0 kg ha-1 in T1, to T8 treatments, respectively. In wet season, NPKSZn were applied at 22-3-19-5-0, 28-3-19-5-0, 28-4-19-5-0, 28-3-24-5-0, 22-4-24-5-0, 28-4-24-5-0, 17-2-14-4-0 and 0-0-0-0-0 kg ha-1 in T1, to T8 treatments, respectively. The total amounts of P as triple superphosphate, K as KCl and S as gypsum, were applied as basal-immediately before transplanting of rice. In the recommended practice for rice, N was applied as urea in three equal splits at basal, 25-30 days after transplanting (DAT) and 5-7 days before panicle initiation (PI) stage and at basal, 20-25 DAT and 5-7 days before panicle initiation (PI) stage in dry season. In wet season, N fertilizer was applied as urea in two equal splits at basal and 5-7 days before panicle initiation stage after drainage out of flood water. Unit plot size was 20 m2 (4 m × 5 m). All plots were surrounded by permanent bunds to prevent transfer of soil and nutrients between plots. In all cases, rice was transplanted and grown on submerged soil with irrigation. Weeds and insects were controlled to avoid yield losses.

 

Soil and plant sampling and analysis

 

Initial soils were collected before land preparation with an auger with 5 cm internal diameter in the plough layer (0–15 cm) at nine randomly selected locations and then mixed as one sample. All fresh soil samples were air-dried, ground and passed through a 2-mm sieve and prepared for routine analyses of texture, pH, organic carbon, total N, available K, P, S and Zn using the methods described by Islam, 2009; Islam et al., 2013a; Islam et al., 2013b; Islam et al., 2014; Islam et al., 2016 and Saha et al., 2016.

Grain yield was recorded from the central 5 m2 harvest area in each plot at maturity and reported on 14% moisture basis. At maturity, 16 hills (four hills from each of the four sides of the grain harvest area) were collected at ground level and fresh straw weight was determined after separating the grains. Grain and straw were dried at 70°C to constant weight and dry weights were recorded. The ratio of fresh and oven-dry weights of straw for 16-hill samples was then used to determine straw yields on an oven-dry basis from fresh straw weights (Islam et al., 2015 and Islam et al., 2016b. Dry grain and straw from the 16-hill samples were ground to pass through a 0.5-mm sieve and analyzed for total N, P and K following standard procedure. The N, P and K contents in grain plus straw were taken as the measure of total N, P and K uptake.

Total N was determined following Micro Kjeldahl method (Bremner, 1965). Plant samples were digested using the HNO3-HCLO4 (5:2) di-acid mixture. Phosphorous was determined colorimetrically by spectrophotometer (model-V-630, Jasco) and potassium was determined by flame photometer (model-410, Sherwood) according to the procedure described by Yoshida et al. (1981).

Agronomic efficiency of nitrogen (AEN) was calculated by using following equations (Islam et al., 2016):

 

 

Where, YNA and YN0 are grain yield (kg ha-1) in fertilized and unfertilized plots, respectively, and NRN is the rate of nitrogen applied (kg ha-1). Mean value of grain yield (Table 1) for each treatment was considered for calculation.

 

Data analysis

 

Analysis of variance (ANOVA) was performed on yield and N, P and K uptake to determine the effects of different treatments using the IRRISTAT software version 4.1 (IRRI, 1998). Least significant differences (LSD) test at the 0.05 level of probability was used to evaluate the differences among treatment means.

 

Results and discussion

 

Yield

 

Applied fertilizer significantly influenced the grain and straw yield of Boro and T. Aman rice (Table 1). In dry season (2011-12), the lowest grain and straw yield were found in T8 treatment. The highest grain yield 7.34 (t ha-1) was obtained with treatment T6, which was statistically similar to T1, T2, T3, T4, T5 and T7 (Table 1). Rahman (2001) reported that in rice-rice cropping pattern, the highest grain yield of rice was recorded in the soil test basis (STB) NPKSZn fertilizers treatment. The highest straw yield (6.47 t ha-1) was observed in the treatment T6, which was statistically similar to the treatments T1, T2, T3, T4 and T5. So, STB dose of fertilizer is enough to get maximum yield. In wet season (2012), the highest grain yield (1.90 t ha-1) was obtained with treatment T2. The lowest grain yield (1.07 t ha-1) was observed in treatment T5 which was statistically similar to T1, T3, T4, T7 and T8. The highest straw yield (7.67 t ha-1) was obtained with the same treatment T2, which was statistically similar to T3, T6, and T7. The lowest straw yield (4.62 t ha-1) was observed in treatment T5, which was statistically similar to T4 and T8. So, 25% additional N fertilizer was required for attaining maximum rice yield in wet season. Islam et al. (2016) also reported that 25% additional N fertilizer is required for getting the highest rice yield in submergence ecosystem (AEZ-3). The highest annual grain yield (8.92 t ha-1 crop-cycle-1) was obtained with treatment T2, but annual grain yield might be increased if we follow STB dose in dry season and 25% additional N fertilizer in wet season. It was observed that these treatments performed better among the treatments on the basis of yield, agronomic efficiency and fertilizer dose. Addition of more nutrients than STB dose might be created nutrient imbalance in soil. As a result, it might have negative impact on rice yield (Anonymous, 2016) and agronomic use efficiency.

 

Table 1. Effect of different fertilizer packages on the yield of rice (t ha-1) in a Boro-Fallow -T. Aman cropping pattern in non-saline tidal flood ecosystem, 2011-12.

 

Treatments
	Boro (BRRI dhan29), 2011-12		T. Aman (Sada mota), 2012		Annual yield (t ha-1 crop-cycle-1)
	Grain	Straw	Grain	Straw	Grain	Straw
T1 = NPKSZn (STB)¶	7.26	5.75	1.26	6.41	8.52	12.16
T2 = T1+ 25% N	7.02	6.20	1.90	7.67	8.92	13.87
T3 = T1+ 25% NP	6.97	6.35	1.28	6.70	8.25	13.05
T4 = T1+ 25% NK	7.14	5.79	1.08	5.49	8.22	11.28
T5 = T1+ 25% PK	6.98	5.80	1.07	4.62	8.05	10.42
T6 = T1+ 25% NPK	7.34	6.47	1.44	6.98	8.78	13.45
T7 = 75% of T1	7.10	4.70	1.36	7.53	8.46	12.23
T8 = Control	3.57	2.27	1.25	5.73	4.82	8.00
LSD0.05	0.78	0.89	0.25	1.17	-	-
Significant level	**	**	**	**	-	-
CV (%)	6.7	9.4	10.9	10.4	-	-

¶Nutrient rates for T1= N162 P11 K58 S11Zn0 (Boro) and T1= N22*** P3 K19S5 Zn0 (T. Aman)

**: Significant at 1% probability level

***50% N of STB was applied

 

 

 

 

Table 2. Effect of different fertilizer packages on the nutrient uptake (kg ha-1) by rice in a Boro – Fallow – T. Aman cropping pattern in non-saline tidal flood ecosystem, 2011-12.

 

Treatments	Nutrient uptake (kg ha-1)						Total nutrient uptake (kg ha-1 crop-cycle-1)
	Boro 2011-12			T. Aman 2012
	N	P	K	N	P	K	N	P	K
T1=NPKSZn(STB)¶	93.18	12.88	134.50	38.93	8.02	155.76	132	21	290
T2 = T1+25% N	111.33	12.66	136.24	55.47	10.88	188.72	167	24	325
T3 = T1+25% NP	107.97	13.00	133.44	45.80	8.59	189.79	154	22	323
T4 = T1+25% NK	102.04	13.87	123.66	42.00	7.66	139.80	144	22	263
T5 = T1+25%PK	85.91	12.22	134.91	30.77	7.01	121.96	117	19	257
T6 = T1+25% NPK	110.15	13.53	167.06	48.41	9.15	183.93	159	23	351
T7 = 75% of T1	90.22	11.10	138.60	40.40	9.61	213.37	131	21	352
T8 = Control	43.72	6.08	57.45	44.92	8.26	152.49	89	14	210
LSD0.05	20.60	1.76	20.18	18.73	2.07	37.27	-	-	-
Significant level	**	**	**	*	*	**
CV (%)	12.6	8.5	9.0	24.7	13.7	12.7

¶Nutrient rates for T1= N162 P11 K58 S11Zn0 (Boro) and T1= N22*** P3 K19S5 Zn0 (T. Aman)

*and** : Significant at 5 and 1% probability levels,respectively. 

*** 50% N of STB was applied

 

Nutrient uptake and agronomic efficiency

 

Applied fertilizer significantly influenced the nutrient uptake by Boro and T. Aman rice of the cropping pattern (Table 2). In dry season, the highest N uptake was observed in T2 treatment, which was statistically similar with T1 (STB), T3, T4, T6 and T7. Statistically similar P and K uptake were observed in STB dose of fertilizer treatment and other treatments, where 25% additional P and K fertilizers were applied. So, STB doses of fertilizers were enough to achieve the maximum rice yield in dry season. In wet season, statistically similar N uptake was found in STB fertilizer treatment and 25% additional N fertilizer treatments. But P uptake was found higher in T2 treatment than STB fertilizer treatment. The highest K uptake was found in T2 treatment, which was statistically similar to T1, T3, T6 and T7.

The highest total NPK nutrient uptake (kg ha-1 crop-cycle-1) was observed in treatment T2. The lowest total NPK nutrient uptake (kg ha-1 crop-cycle-1) was observed in treatment T8 (Table 2). It was observed that more nutrient application had no extra benefit for nutrient uptake as well as rice yield in dry season. The highest agronomic efficiency was found with T­1 and T2 treatments in dry and wet season, respectively (Table 3). Islam et al. (2016) also reported that STB dose of fertilizer and 25% additional N fertilizer treatment gave the highest agronomic efficiency in non-saline tidal flood ecosystem and submergence ecosystem, respectively.

Table 3. Effect of fertilizer doses on agronomic efficiency (kg/kg) in dry and wet season, 2011-12.

 

Treatments	Agronomic efficiency (kg/kg)
	Dry season	Wet season
T1=100% NPKSZn (STB)¶	22.8	0.5
T2= T1+ 25% N	17.0	23.2
T3=T1+ 25% NP	16.7	1.1
T4=T1+ 25% NK	17.6	-
T5=T1+ 25% PK	21.0	-
T6=T1+ 25% NPK	18.6	6.8
T7=75% of T1	28.9	6.5
T8=Control	-	-

¶Nutrient rates for T1= N162 P11 K58 S11 Zn0 (Dry season) and T1= N22*** P3 K19 S5 Zn0 (Wet season)

*** 50% N of STB was applied.

Conclusion

 

On the basis of yield performance, nutrient absorption and agronomic efficiency, the treatment T1 = N162 P11 K58 S11 for dry season and treatment T2 = N28 P3 K19 S5 for wet season performed the best among different doses of fertilizer treatments in non-saline tidal flood ecosystem. From the result it is observed that present recommended dose of fertilizer for wet season is not sufficient to obtain optimum yield. So, 25% more N fertilizer is required to obtain better yield for wet season in this ecosystem.

 

Acknowledgment

 

We are very much thankful to the authority of “NATP” for providing all facilities and support to meet our study requirements. We are grateful to the farmers of saline and char land ecosystem for their patience and excellent cooperation in conducting the on-farm experiments.

 

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