Comparison Between Fertilizer Rate Using Soil Analysis and Farmer Practices in Commercial Seed Production in North East Thailand

Adams Enterprises Ltd., 193/23 4^th Floor Lake Rajada Office, Klongtoey, Bangkok, Thailand 10110

Most of Northeastern Thailand has been taken for agricultural fields. Farmers grow crops all the year in the same areas, slowly deteriorating soil quality from unbalanced application of chemical fertilizer in increase amounts. In 2009, the average import of chemical fertilizer was 3,867,187 tons. Recently, demand of applied fertilizer has continually increased (Office of agricultural economics, Thailand, 2010). Therefore, the optimum fertilizing and improvement to good soil are priorities that needs to be realized.

Soil fertility depends on difference factors such as essential plant nutrients, organic matter, pH, soil structure and organism. The macronutrients are nitrogen (N), phosphorus (P) and potassium (K). The secondary plant nutrients are calcium (Ca), magnesium (Mg) and sulfur (S). The micronutrients, plant need in small quantities are boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn) (Tucker, 1999). Many research results showed fertilizer application to optimize the yield in several crops such as seed yields of jojoba were increased by N rate in 4 of the 7 years that crops were produced for 10 years (Nelson and Watson, 2001). Application of N and K fertilizers (750 kg N and 300 kg K₂O ha⁻¹) increased yields of kidney bean when studied for 3 years (Zhao-Hui et al., 2008). Alsafar and Al-Hassan (2009) reported 75 kg N and 50 kg P₂O₅/ha increased the total dry matter and essential oil yield of Indigenous Mint (Mentha longifolia L.).

The objective in this study was to study soil fertility following ASI suggestion on plant growth, seed yields and seed quality of tomato and sweet pepper seed production and study the optimum fertilizer application to minimize cost (Portch and Hunter, 2002). Moreover, saving chemical fertilizer thereby reducing any possible environmental damage.

Sweet pepper seeds were planted in a field at Sakon Nakhon province and tomato seeds were planted in a field at Khonkean province, in Northeastern Thailand. Soil samples were taken and mixed from 20 randomized points in each field then air dried. A small sub-sample from each field sample was properly selected and this sample of approximately 150 g was sent together with attached soil document for analysis by Agro Services International Inc., Florida, USA (ASI). All treatments depended on a difference of fertilizer rate applied based on the ASI suggestion as follow;

One week before transplanting seedling, 60% of 15-0-0 fertilizer, cow manure and other nutrients following ASI suggested were mixed in bed preparing and then 20% 46-0-0 fertilizer was put after transplanting at 2, 5 and 7 (Treatment 2 and 4 only) weeks, respectively. Furrow water system and net house were used for both crops. The experimental design was a completely randomized design (CRD). The plants were randomized 10 plants in each treatment for observation. Data recorded were plant height, seed yields and seed quality. Germination test used the paper test.

In tomato field, it was found that after transplanting for 2-4 weeks had significant of plant height but by 5^th week plant height and growth had no significant differences among treatments. Tomato that has fertilizer applied following ASI suggested rate plus 20% of 46-0-0 fertilizer and cow manure had double the number of fruit (115 fruits/plant) and seed yield (3.57 grams/plant) higher than tomato from farmer’s practice (50 fruits/plant and 1.72 grams/plant). However, all treatment had no significant differences in germination rate. In the sweet pepper field, after transplanting, height of plants in all treatments had no difference, but those from farmer’s practice had higher of plant height than other treatments. At pollinating stage and with high plants in the farmer’s practice, started pollination before the other treatments had dropped flower. As a result, the farmer’s practice had a low of number of fruit. The comparison among treatments showed treatment 4 had the highest number of fruit (6.4 fruits/plants) which related to high seed weight. Moreover, frequency of fertilizer had no effect on seed yield (comparisons between treatment 3 and 4) (Table 2). However, sweet pepper seed in all treatments had good quality. Application of chemical fertilizers combined with manure application increased the yield and nitrogen use efficiency of rice (Ming-gang et al., 2008) and increasing N from 0 to 100 kg and wheat straw and compost at 50 ton ha^-1 compost treatment can increase seed yield of winter canola (Kazemeini et al., 2010). Seeding rapeseed from 29 April to 9 May had a greater assurance for higher yields and 160 kg N ha1 produced near-maximum seed yields (Ozer, 2003). Soy bean were grown with N, P and K fertilizer (N-P-K 25-25.8-16.6 kg. ha^-1) plus farmyard manure at 10 t.ha^-1 on dry weight basis had root biomass, root length and grain yield greater than application of N, P and K and no fertilizer (Mandal et al., 2009).

Fertilizer following ASI suggested rates plus 20% of 46-0-0 fertilizer and cow manure applied to tomato and sweet pepper crops increased number of fruit and seed yield more than the farmer’s practice. Therefore, the efficiency of fertilizing based on soil test recommendations, on quantity and quality of seed production depends on variety of plant, weather and method of fertilizing. Cow manure accelerated plant growth. Further refinements of these results are necessary to reach better practices to recommend to farmers to improve fertilizer use efficiency.

Alsafar, M.S. and. Al-Hassan Y.M. 2009. Effect of nitrogen and phosphorus fertilizers on growth and oil yield of indigenous mint (Mentha longifolia L.). Biotechnology 8: 380-384.

Kazemeini, S.A. Hamzehzarghani, H. and Edalat, M. 2010. The impact of nitrogen and organic matter on winter canola seed yield and yield components. Aust. J. Crop Sci. 4(5):335-342.

Mandal, K.G., Hati, K.M and Misra, A.K. 2009. Biomass yield and energy analysis of soybean production in relation to fertilizer-NPK and organic manure. Biomass Bioenerg. 33:1670-1679.

Ming-gang, X., Dong-chu, L., Ju-mei, LI., Dao-zhu, Q., Kazuyukib, Y. and Hosenb, Y. 2008. Effects of organic manure application with chemical fertilizers on nutrient absorption and yield of rice in Hunan of Southern China. J. Agric. Sci. Chin. 7(10):1245-1252.

Nelson, J.M. and Watson, J.E. 2001. Nitrogen fertilization effects on jojoba seed production. Industrial Crops and Products 13:145-154.

Ozer, H. 2003. Sowing date and nitrogen rate effects on growth, yield and yield components of two summer rapeseed cultivars. Europ. J. Agronomy. 19:453-463.

Portch, S. and Hunter, A. 2002 A Systematic Approach to Soil Fertility Evaluation and Improvement. Canpotex, HongKong.

Tucker, M. R. 1999. Essential Plant Nutrients: their presence in North Carolina soils and role in plant nutrition. www.ncagr.gov/agronomi/pdffiles/essnutr.pdf.

Table 3. Height of tomato field after transplanted 2-5 weeks.

Table 4. Seed yield (g/pl), 1,000 seeds weight (g), average of fruit (fr/pl) and germination rate (%) of tomato field.