Adequate potash improves rice production economics in Assam, Tripura and West Bengal
Negative soil potassium (K) balances continue to occur at an alarming pace in the Eastern states of India due to application rates that fail to match quanities contained within harvested crop products. This is a direct cause of loss in soil fertility and sustainability in our agricultural production systems. Inadequate fertilization of crops is restricting the full exploitation of genetic potential of crops and further hindering farmers profit and rural development. For adequate and correct use of potash, farmers continuously need proven and practical information either directly or through farm advisory services, soil and plant testing laboratories, trainers, mass media, etc. PPIC-India Programme, in collaboration with industry stakeholders, conceived a nation-wide initiative to address the lack of awareness regarding the importance and use of potassium in Indian agriculture through Field Demonstrations, Field Days, Farmers’ Training Programmes, Potash Promotion Campaigns, Dealers/Retailers Training Programmes as well as development and distribution of extension literatures for different target groups. A series of field trials across the eastern states showed encouraging results and can act as vital tool for increasing awareness leading to reversal of crop productivity stagnation/decline in these states.
The available potassium status of the soils of West Bengal, Tripura and Assam (Table 1), shows that majority of the soils belong to low or medium categories and adequate and balanced use of potash is necessary to arrest the decline in K fertility status of soils and for improving agricultural productivity in these states. This is particularly true for Assam and Tripura where K2O consumption per unit of gross cropped area is quite low.
Table 1. Status of available potash in soils of Assam, Tripura and West Bengal
State | No. of samples | Potassium fertility status in percent samples |
Low | Medium | High |
West Bengal | 254060 | 32 | 45 | 23 |
Tripura | 18443 | 67 | 25 | 8 |
Assam | 245 | 26 | 52 | 22 |
Source: Karmakar et al. (2002) for Assam, Datta & Laskar (1999) for Tripura and Ali (2005) for West Bengal
Estimates made by various sources point out that extent of negative soil K balances in these states is alarming (Table 2). Potassium is affected the most among the three major plant nutrients due to very low use of potash. Programmes to convey the importance of K in a balanced fertilization strategy to improve the yield, produce quality, and farmers profit would do much to help change the situation.
Table 2. Extent of nutrient mining in Assam, Tripura and West Bengal ('000 tonnes).
State | N | P2O5 | K2O |
West Bengal | (-) 251.3 | (-) 193.7 | (-) 656.9 |
Tripura | (-) 28.6 | (-) 3.1 | (-) 31.6 |
Assam | (-) 218.7 | (-) 58.7 | (-) 276.5 |
Source: Borkakati et al. (2001) for Assam, Sharma & Shukla (2001) for Tripura and
Majumdar & Tiwari (2001) for West Bengal
Field demonstrations were conducted on farmers’ fields in Assam, Tripura, and West Bengal to create awareness about the importance of potash to achieve the targets of high yield, high produce quality and high farmer profit. Results are summarized in Table 3. Application of 150% of the state recommended fertilizer dose produced maximum yields in most of the cases. It is also apparent that skipping potassium (SR-NP) caused a yield decline to the tune of 400 to 1,100 kg/ha...a major loss for farmers. Considering the cost of cultivation being same, a comparative study to calculate the benefits of K application reveals an extra profit of Rs.1,878 to Rs.5,098 per hectare for state recommended K rates, and Rs.2,449 to Rs.9,794 for the treatment providing 150% of the state recommended NPK dose.
Organisation of Field Days at the experimental sites is an integral part of the programme as it helps spread the message of the importance of potash in balanced fertilization to the masses without any time lag. In most of the cases, the comparative effects of with and without K plots were remarkable. At some sites, potash use dictated the success of the crop. For instance, in Sildubi Village of Assam, flood water entered the field twice during mid crop season and there was severe lodging in the two plots having no potash application. Plots treated with 100% K and 150% of recommended doses of potash withstood these adverse water conditions. Such visual evidences helped farmers understand the importance of potash in negating the adverse effect of biotic and abiotic stresses leading to better yield and profit.
Potassium is one of the three main pillars of balanced fertilizer use, along with N and P. Greater and efficient use of potash is a must for sustaining high crop yields and maintaining soil health.
Table 3. Yield and profit increase in field trials
Village | Yield (t/ha) | Extra profit over NP (Rs./ha) |
FP | SR-NP | SR-NPK | SR-150% NPK | SR-NPK | SR-150% NPK |
Assam |
Sonapur Pathar | 4.1 | 4.2 | 4.6 | 4.5 | 1816 | 237 |
Sarpara | 4.8 | 5.0 | 5.6 | 6.6 | 2876 | 7127 |
Kasutali | 3.7 | 4.3 | 4.5 | 4.4 | 756 | -823 |
Kasutali 1 | 3.8 | 4.0 | 4.5 | 4.5 | 2346 | 1297 |
Parlihodongpur | 5.2 | 5.0 | 5.7 | 6.6 | 3406 | 7127 |
Sildubi 1 | 4.0 | 4.3 | 4.4 | 4.6 | 431 | 542 |
Sildubi 2 | 4.1 | 4.3 | 4.5 | 4.6 | 961 | 542 |
Sildubi 3 | 3.0 | 4.2 | 4.2 | 4.5 | -99 | 542 |
Borchapari | 3.7 | 3.6 | 4.3 | 4.5 | 3406 | 3417 |
Makum Balijan | 3.3 | 3.2 | 3.8 | 4.0 | 2876 | 2887 |
Mean | 4.0 | 4.2 | 4.6 | 4.9 | 1878 | 2449 |
Tripura |
West Charakbai 1 | 6.0 | 5.2 | 5.8 | 6.9 | 3196 | 7762 |
West Charakbai 1 | 6.5 | 4.7 | 6.0 | 6.8 | 6906 | 9882 |
West Charakbai 1 | 6.1 | 4.3 | 5.7 | 7.1 | 7436 | 13592 |
West Charakbai 1 | 6.4 | 5.4 | 5.6 | 7.2 | 1076 | 8292 |
West Charakbai 1 | 6.3 | 5.1 | 5.5 | 6.6 | 2136 | 6702 |
Paschim Singhi Cherra | 4.3 | 3.0 | 4.4 | 5.3 | 7114 | 10942 |
Mean | 5.9 | 4.6 | 5.5 | 6.7 | 4644 | 9794 |
West Bengal |
Gangapur | 4.0 | 3.0 | 4.5 | 3.6 | 7306 | 554 |
Jordighi | 3.8 | 3.3 | 5.2 | 7.0 | 9426 | 16984 |
Tajpur | 3.8 | 3.6 | 4.2 | 4.5 | 2536 | 2144 |
Betna | 5.4 | 5.2 | 5.5 | 5.8 | 946 | 554 |
Changual | 6.2 | 5.0 | 6.0 | 7.1 | 4656 | 8504 |
Bankathi | 4.4 | 3.4 | 4.8 | 5.3 | 6776 | 7444 |
Mean | 4.6 | 3.9 | 5.0 | 5.6 | 5098 | 6296 |
FP: Farmers’ Practice; SR-NP: State recommended N & P; SR-NPK: State recommended N, P & K;
SR- 150% NPK: 150% of State recommended N, P & K
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