Luận án Nghiên cứu biện pháp kỹ thuật nhằm tăng năng suất và hiệu quả sản xuất lạc (Arachis Hypogaea L.) trên đất cát biển tỉnh Quảng Bình

%). Nhận thức của người nông dân khá đầy đủ về các vấn đề khó khăn trong sản xuất lạc và đã chỉ ra được một số hướng giải quyết, khắc phục. Tuy nhiên, sản xuất lạc trên loại đất này hiện nay năng suất và hiệu quả kinh tế còn thấp do các yếu tố hạn chế sau: - Đất cát biển có độ phì tự nhiên thấp. Đa số các yếu tố dinh dưỡng cần thiết cho sinh trưởng phát triển của cây lạc đều thuộc loại rất nghèo đến nghèo. Và kết quả thực nghiệm cho thấy K và P là hai yếu tố dinh dưỡng hàng đầu hạn chế năng suất lạc. Trong khi đó, việc bón phân của người nông dân vẫn còn tùy tiện, do chưa có quy trình phân bón cho lạc riêng cho vùng đất cát biển Quảng Bình. - Trong khi, điều kiện thời tiết diễn biến phức tạp, sản xuất lạc đang dựa hoàn toàn vào nước trời và chưa có nghiên cứu thời vụ gieo lạc cho vùng đất cát biển, nên Sở Nông Nghiệp và PTNT Quảng Bình hướng dẫn khung thời vụ gieo lạc vụ đông xuân hiện nay còn khá rộng, từ ngày 15/12 đến ngày 25/02. Đây là một trong những nguyên nhân sản xuất lạc ở vùng này cho năng suất và hiệu quả kinh tế thấp. 1.2. Xác định được tổ hợp phân bón cân đối, hợp lý giữa vô cơ với hữu cơ cho lạc trồng trên đất cát biển tỉnh Quảng Bình vừa tăng năng suất và hiệu 23 quả kinh tế là: 40 kg N + 120 kg P2O5 + 80 kg K2O/ha + 500 kg vôi/ha + 10 tấn phân chuồng/ha cho năng suất quả đạt 3,1 – 3,113 tấn/ha, lãi ròng đạt 25,38 – 29,18 triệu đồng/ha, tỷ suất lãi so với vốn đầu tư đạt 0,51 – 0,53; hoặc có thế thay phân chuồng bằng phân hữu cơ vi sinh với lượng 0,6 tấn/ha cũng bảo đảm cho năng suất quả đạt 2,628 – 2,68 tấn/ha, lãi ròng đạt 19,39 – 25,91 triệu đồng/ha, tỷ suất lãi so với vốn đầu tư (RR) đạt 0,42 – 0,5. 1.3. Xác định được khung thời vụ gieo trồng lạc thích hợp nhất cho vùng đất cát biển tỉnh Quảng Bình trong vụ đông xuân là từ ngày 04/01 đến ngày 03/02. Trong khung thời vụ này sản xuất lạc cho năng suất thực thu đạt 1,81 – 2,178 tấn/ha và bảo đảm thu được hiệu quả kinh tế. 1.4. Xác định được việc áp dụng biện pháp phủ đất trong sản xuất lạc vừa tăng năng suất và hiệu quả kinh tế vừa cải thiện nhiều tính chất lý, hóa của đất. Phủ đất cho năng suất quả tăng 0,395 – 0,482 tấn/ha, lãi ròng tăng 7,966 – 10,01 triệu đồng/ha, chỉ số RR tăng 0,14 – 0,17 so với không phủ đất. So sánh hai loại vật liệu thì phủ đất bằng rơm phù hợp hơn vì vừa giảm được chi phí sản xuất do tận dụng được nguồn rơm sẳn có vừa cải thiện độ phì cho đất. 1.5. Mô hình thực nghiệm bằng việc áp dụng đồng thời các biện pháp kỹ thuật của đề tài xác định được đã cho kết quả vượt trội về năng suất và hiệu quả kinh tế so với quy trình sản xuất hiện tại. Năng suất tăng từ 2,95 tấn/ha tăng lên 3,335 – 3,743 tấn/ha (tăng 59 - 79%) và lãi ròng từ 8,19 triệu đồng/ha tăng lên 38,83 - 46,89 triệu đồng/ha và chỉ số RR từ 0,17 tăng lên 0,76 – 0,87. 2. Đề nghị 2.1. Triển khai ứng dụng nhanh biện pháp kỹ thuật canh tác tổng hợp mà đề tài đã xác định nhằm tăng năng suất và hiệu quả kinh tế cho người nông dân trồng lạc trên đất cát biển tỉnh Quảng Bình. Đây là cơ sở cho việc khuyến khích mở rộng diện tích trồng lạc và khai thác tiềm năng của vùng đất này. 24 2.2. Bón phân hữu cơ trong sản xuất lạc trên đất cát biển là yêu cầu quan trọng bảo đảm sản xuất ổn định và bền vững. Vì vậy, cần khuyến khích sản xuất các loại phân hữu cơ từ chất thải chăn nuôi, than bùn, phụ phẩm nông nghiệp,.... CÁC CÔNG TRÌNH KHOA HỌC ĐÃ CÔNG BỐ CÓ LIÊN QUAN ĐẾN LUẬN ÁN 1. Nguyễn Minh Hiếu, Lê Thanh Bồn, Hồ Khắc Minh (2011), Những tiềm năng và thách thức cho phát triển sản xuất lạc trên đất cát biển tỉnh Quảng Bình, Tạp chí Nông nghiệp và PTNT, 7, trang 3 – 7. 2. Hồ Khắc Minh, Nguyễn Minh Hiếu (2012), Nghiên cứu ảnh hưởng của thời vụ gieo trồng đến sinh trưởng và năng suất giống lạc L14 trong vụ đông xuân trên đất cát biến tỉnh Quảng Bình, Tạp chí Nông nghiệp và PTNT, 10, trang 12 – 20. 3. Lê Thanh Bồn, Hồ Khắc Minh (2012), Nghiên cứu ảnh hưởng của các tổ hợp phân bón đến năng suất giống lạc L14 trồng trên đất cát ven biến tỉnh Quảng Bình, Tạp chí Nông nghiệp và PTNT, 10, trang 59 – 67. MINISTRY OF EDUCATION AND TRAINING HUE UNIVERSITY  HO KHAC MINH RESEARCH INTO TECHNICAL METHODS TO INCREASE THE YIELD AND PRODUCTION EFFICIENCY OF PEANUT (Arachis hypogaea L.) ON ARENOSOLS SOIL IN QUANG BINH Academic field: Cultivation Ref No: 62.62.01.01 DOCTORAL THESIS HUẾ, NĂM 2013 This research was completed at HUE UNIVERSITY Name of supervisors: 1. Ass Prof. Dr. Nguyen Minh Hieu 2. Dr. Le Thanh Bon Reviewer 1: Prof. Dr Reviewer 2: Prof. Dr Reviewer 3: Dr This thesis will be defended to academic evaluation committee of the Hue University, held at: At…… AM, August 2014 The thesis can be found at: 1. National Library 2. Library of Hue University 3. Library of Hue University of Agriculture and Forestry 1 PREAMBLE 1. Background Peanut (Arachis hypogaea L.) are annual industrial crops being grown on a large area and bring about high production with a great deal of nutrient value. In Vietnam as well as on the world, peanut growing areas have slowly increased since 1995. The soil area for growing peanut steadily takes up around 250,000 hectares/year in Vietnam; however, it’s yield gradually increased from 334,500 tons in 1995 to 485,800 tons in 2010. Like many other countries worldwide, in Vietnam this significant increase is thanks to the investment on studies selecting and creating new varieties such as MD7, MD9, L08, L12, L14, L18, LVT, L23, L26, etc. The varieties have capability of confronting harsh conditions outside and result in high yield and good quality. Besides, studies on technical measures like density, fertilizer, soil coverage were carried out to apply appropriately to every kind of new variety and crop on a particular ecological area. Peanut plays an essential part in plant structure in Quang Binh. They are mainly grown on grey, loamy and arenosols soil and occupies about 5,500 hectares. At present, the area of unexploited arenosols soil is rather large, approximately there are 6,000 hectares left. Although provincial authorities have given polities on seed price aid and the use of advanced varieties produced by high technique like MD7, L14, L18, L23, etc reaches a good rate, average yield obtained 1.57 tons/hectare. This figure significantly lowers in comparison with common average of the whole country (1.99 tons/hectare). In addition, the cultivation process recommendations of peanut production still follow the common one of Ministry of Agriculture and Rural Development, there is no specific one for Quang Binh province. All above reasons have hurried us to carry out the study titled ‘Research into technical methods to increase yield and production efficiency of peanut (Arachis hypogaea L.) on arenosols soil in Quang Binh’. 2 2. Study Objectives - Assess factors restricting peanut yield on arenosols soil by evaluating current peanut production on arenosols soil in Quang Binh. - Find out some optimal technicals for building up cultivation process in order to increase yield and production effect of peanut on arenosols soil in Quang Binh. 3. Scientific and practical value of the research 3.1. Scientific value - The results of the research would make contributions to the development of scientific base for managing, using and utilizing properly arenosols soil of Quang Binh. - The results of the research would be scientific database which helps the provincial managers give appropriate support polities on developing the peanut production on arenosols soil. 3.2. Practical value - Scientists and technicians would use the results of the research as reference resources to train farmers the peanut growing techniques. - The results of the research applied to production will increase yield and economic efficiency in the peanut production on arenrosols soil in Quang Binh province. - The results of the research will make contributions to the gradual improvement of soil, towards sustainable production and income increase for farmers. 4. Subjects of the study 4.1. Location of the study - Investigations were carried out in districts and cities in the coastal areas of Quang Binh. - Experiments and demonstrations were implemented in Cam Thuy commune of Le Thuy district and Quang Xuan commune of Quang Trach district in Quang Binh province. 3 4.2. Research period From June 2009 to June 2013 4.3. Scope of the study - The study only focused on a number of cultivation techniques as a basis to build a new cultivation process ensuring yield increase, economic efficiency and sustainability of growing peanuts on arenosols soil in Quang Binh. - The study was carried out only in the winter spring seasons, based on rainfed conditions. 5. New findings and contributions of the thesis - The survey results of the thesis supply the researcher with reliable data in order to evaluate the advantages and difficulties influencing on the yield and efficiency of peanut production on arenosols soil in Quang Binh province. - The researcher determined reasonable balance of the fertilizer complex between inorganic and organic for peanut production on arenosols soil in Quang Binh with the aim of increase in yield and economic efficiency and improvement in soil’s chemical characteristics. - The optimum planting time frame for peanut production in winter spring season on arenosols soil in Quang Binh was defined is from date 04/01 to date 03/02. - Research results showed that the use of soil mulching materials for peanut production in winter spring season on arenosols soil in Quang Binh was meant to increase more yield, economic efficiency and improve soil physical and chemical characteristics than the one without mulch. Comparing two kind of materials, straw mulch is more suitable than mulch plastic in peanut production. - Applying integrated technical method assessed by this research brings about much more positive results in terms of yield and economic efficiency than the traditional cultivation. 4 6. Structure of the thesis The thesis is presented on 153 pages and divided in seven parts such as: the preamble: 4 pages; Chapter 1 of Background and literature review: 36 pages; Chapter 2 of Materials, Contents and Methodologies: 13 pages; Chapter 3 of Results and discussion: 84 pages; The conclusions and recommendations: 2 pages. In addition, the thesis used 150 reference documents, of which, 98 in Vietnamese and 52 in English. CHARP 1 BACKGROUND AND LITERATURE REVIEW 1.1. An overview of peanut production in the world, Vietnam and Quang Binh 1.2. Studies on arenosols soil in Vietnam 1.3. Scientific Basis for enhancement of crop yields 1.4. Some results of research and applications of advanced techniques in peanut production in the world and Vietnam 1.5. Key summaries from literature review From the year 2000 to now, the peanut area in the world and Vietnam tend to rise slowly, some places being downward trend, but the production quantity is still increasing, mainly due to increased the yield. Peanut yield increase is due to focused research to improve technique factors in peanut production. The study focuses on the techniques of cultivation follows: (i)- Breeding the new varieties, either high yield and suitble each ecological conditions; (ii)- technical solution of integrated plant nutrition. In Vietnam, the ratio of N:P:K most logical in recent years has been identified as 1:3:2, in which, applied to the optimal amount of nitrogen: 30 - 40 kg N/hectare, phosphate > 60 kg P2O5/hectare, potassium: 60 - 90 kg K2O/hectare, calcium: 300 - 500 kg lime/hectare, organic: 5 - 10 tons of manure/hectare (or 300 - 2,000 kg organic- microorganisms fertilizer/hectare); (iv)- Apply mulch in peanut production was confirmed in effect clearly higher yield; (v)- Arranging proper planting time is very important technique. The factors of soil physical characteristics of interest in the production is soil moisture and temperature. 5 CHARP 2 MATERIALS, CONTENTS AND METHODOLOGIES 2.1. Materials - Experimentally grown peanut variety: L14. - Fertilizers: Urea (46% N), Super phosphorous (16% P2O5), KCl (60% K2O), lime, local manure and Song Gianh organic-microorganisms. - Mulching materials: White plastic mulch, paddy straw. - Soil: arenosols soil of Quang Binh province . 2.2. Contents and research methodologies 2.2.1. Assessment of the peanut production reality and determining factors restricting the yield of peanut on arenosols soil in Quang Binh - Baseline survey of peanut production on arenosols soil: Primary data were collected from the households producing peanut on arenosols soil. There are a total of 180 survey sheets, a sheet/household. - Investigation into the reality of arenosols soil to assess the potentials for developing peanut production: we collected secondary data basing on the reports of the provincial and districts. - Experiment to determine the order of nutritional factors restricting peanut yield on arenosols soil in Quang Binh: Experiments were simultaneously implemented in the winter spring 2009 - 2010 at two different places (Tan Tien village and Tan Phong village of Cam Thuy commune, Le Thuy district, Quang Binh province). The experiment consists of four formulas: Formula 1 (Control), 500 kg lime + 30 kg N + 90 kg P2O5 + 60 kg K2O/ha; Formula 2, Control - nitrogen; Formula 3, Control –phosphate; Formula 4, Control - potassium. The experiments were set up by Random Completed Block Design (RCBD), with 3 replications. The area of each plot was 20 m2. 2.2.2. Research to determine the appropriate combination of fertilizers for growing peanuts on arenosols soil in Quang Binh - Research to determine the appropriate combination of inorganic 6 fertilizer and manure: The experiments were implemented 2 times, the 1st in the winter spring 2010 – 2011 at Cam Thuy commune, Le Thuy district and the 2nd in the winter spring 2011 – 2012 at Quang Xuan commune, Quang Trach district in Quang Binh). The experiment consists of 12 formulas: the formulas 1, 2, 3, 4 fertilized with inorganic fertilizer 20 kg N + 60 kg P2O5 + 40 kg K2O + 500 kg lime/ha; the formulas 5, 6, 7, 8 fertilized with inorganic fertilizer 30 kg N + 90 kg P2O5 + 60 kg K2O + 500 kg lime/ha; the formulas 9, 10, 11, 12 fertilized with inorganic fertilizer 40 kg N + 120 kg P2O5 + 90 kg K2O + 500 kg lime/ha; Accordingly, formulas in the same group of inorganic fertilizers are fertilized vary in the amount of manure in turn is 0 ton/ha, 5 tons/ha, 10 tons/ha and 15 tons/ha. The experiments were set up by Random Completed Block (RCB), with 3 replications. The area of each plot was 10 m2. - Research to determine the appropriate combination of inorganic fertilizer and organic-microorganisms: The experiments were carried out the same as experiments of Research to determine the appropriate combination of inorganic fertilizer and manure but changing manure by organic- microorganisms fertilizer, the amount respectively to 0 ton/ha and 0.3 tons/ha, 0.6 tons/ha and 0,9 tons/ha. 2.2.3. Research to determine the optimum planting time frame for peanut in the winter-spring on arenosols soil in Quang Binh The experiments were implemented 2 times consecutively on arenosols soil in Quang Binh, in the winter spring 2009 – 2010 and the winter spring 2010 – 2011 at Cam Thuy commune, Le Thuy district. The experiment consisted of eight formulae for planting at different times designed as follows: the first formula was planted on 15 December, the next six formulae were planted 10 days apart and the latest one was planted on 23 February. The experiment design was a Randomized Complete Block, with three replications. The area of each plot was 20 m2. 7 2.2.4. Research results of the soil mulching application for peanut production in the winter spring on arenosols soil in Quang Binh Experiments of research simultaneously were implemented in the winter spring 2011 - 2012 at two different places (Cam Thuy commune, Le Thuy district and Quang Xuan commune, Quang Trach district, Quang Binh province). The experiment consists of three formulae: Formula 1(Control) – No mulch; Formula 2 – white plastic mulch; Formula 3 – paddy straw mulch (10 tons/ha). The experiments were set up by Random Completed Block (RCB), with 3 replications. The area of each plot was 10 m2. Fertilizing: 30 kg N + 90 kg P2O5 + 60 kg K2O + 500 kg lime + 5 tons manure/ha. 2.2.5. Building the demonstration model about peanut production on arenosols soil in Quang Binh From the results of the treatments identified the best above established the integrated technical measures and introduced with large-scale production. The model was implemented in the winter spring 2012 - 2013 at Cam Thuy commune, Le Thuy district, Quang Binh province. Empirical model consists of three components: Component 1 (Control) - 30 kg N + 90 kg P2O5 + 60 kg K2O + 500 kg lime + 5 tons manure + No mulch/ha; Component 2 - 40 kg N + 120 kg P2O5 + 90 kg K2O + 500 kg lime + 10 tons manure + mulching with 10 tons paddy straw/ha; Component 3 - 40 kg N + 120 kg P2O5 + 90 kg K2O + 500 kg lime + 0,6 tons organic-microorganisms + mulching with 10 tons paddy straw/ha. Scale of implementation: 2,700 m2 and 9 households engaged (3 households/component). 2.2.6. The monitoring indicators and data analysis method - The monitoring indicators: Indicators of growth and development, the elements of yield, evaluate some soil’s chemical characteristics before and after testing and evaluation of economic efficiency. The seeding density in the experiments was 40 plants/m2. - Data analysis: Using Excel and Statistiz 9.0. 8 CHARP 3 RESULTS AND DISCUSSIONS 3.1. Assessment of peanut production reality and determining factors restricting the yield of peanut on arenosols soil in Quang Binh 3.1.1. Natural conditions and the reality of agricultural production on arenosols soil in Quang Binh 3.1.1.1. The types of arenosols soil in Quang Binh province and a number of their characteristics Quang Binh arenosols soil with an area of 54887.84 hectares, distributed in 29 communes of 5/7 districts of the province. The land is divided into 3 main types with the following characteristics: - Luvic Arenosols: The area of 45,303.84 hectares, accounting for approximately 5.63% of the total area. Distributed along the coast formed the dunes with a height of 2 - 3 m, sometimes up to 50 m. Mechanical composition of the soil is very rough. - Eutric Arenosols: The area of 9,319 hectares, accounting for 1,16% of the total area, distributed in the lower terrain and rather flat. Mechanical composition of the soil is light. - Dystric Arenosols: The area of 265 hectares, accounting for 0.03% of the total area, distributed in some communes of Quang Trach district. General characteristics of the three types of soil is usually acidic reaction; Nitrogen, phosphorus and potassium are poor to very poor; CEC is rather low; low organic content without the Dystric Arenosols (7%). Vegetation consists of wild plants, planted forests and agricultural crops, in that the vegetation of Eutric Arenosols is rich and diverse in species the most. 3.1.1.2. Climatic conditions in Quang Binh province and their effects on the growth and development of peanut Through assessing climatic conditions in Quang Binh province in Table 3.1 shows that in terms of the production based on rainfed, peanut can be facilitate growth and development during winter spring. Peanut 9 production in this case, there are often advantages and disadvantages following: In the early time, climatic conditions is low temperature, low rainfall, less sunshine. Especially, the when very low temperatures, the seed will germinate poorly, leading to lower density, will affect on yield and lost output later. At midseason, good temperature conditions for peanut blossom, entering pegs in the soil and forming pod. At the end of the season, climatic conditions suitable for the pod forms and riping. However, at this time the pod usually germinate and be rotten in the field. Especially for the peanut fields in late time of the winter spring season, because of affected on high soil moisture in Coc Vu – Tieu Man time. Table 3.1. Typical average values of meteorology in several years in Quang Binh Temperature (oC) Air humidity (%) Rain Factor Month Ttb Tmax Tmin Utb Umin Amount of rain (mm) Dates of rain sunny time (hour) 1 18.9 28.0 10.3 88 43 60.9 11.0 92.4 2 19.3 31.7 12.2 90 30 40.4 10.2 72.6 3 21.6 32.3 11.1 90 26 40.8 9.9 102.7 4 24.7 37.4 16.0 87 30 53.8 7.9 160.3 5 24.6 40.5 21.9 82 32 53.4 7.8 160.3 6 29.9 40.2 23.9 78 31 42.7 7.0 222.0 7 29.6 40.5 21.8 70 33 73.0 7.2 227.6 8 28.7 39.6 19.9 76 35 168.2 11.6 182.1 9 26.9 39.0 18.7 84 37 478.0 16.7 175.6 10 24.7 35.1 14.6 86 41 686.0 10.8 142.1 11 22.3 32.7 12.9 86 40 334.4 18.2 99.8 12 19.6 29.0 7.8 86 43 121.3 14.6 90.4 ( Source: Quang Binh Center of Hydro-meteorological Forecast ) 3.1.1.4. The situation of agricultural production on arenosols soil in Quang Binh - The area and using structures on arenosols soil in Quang Binh Data collected in Table 3.2 shows that: There were 36,263.7 ha of agricultural production, accounting for 66% of the total area. The cultivated land was 8955.44 ha, occupied the second position, in which the paddy planted land of 5,114.71 ha. The area has not used much, 5626.87 ha. 10 Table 3.2. The area and using structures on arenosols soil in Quang Binh Order Type of land Area (ha) Ratio (%) 1 Agricultural land 36,263.70 66.1 Cultivated land 8,955.44 16.3 - Paddy planted land 5,114.71 9.3 a - Dry crops planted land 3,840.43 7.0 b Forestry land 26,693.62 48.6 c Aquacultural land 553.93 1.0 d Land of salt production 60.70 0.1 2 Unused land 5,626.87 10.3 3 Other land 12,997.27 23.7 Total 54,887.84 100 - The structure of the annual crops area on arenosols soil in Quang Binh According to the data in Table 3.3: In the annual crops area of 8955.4 hectares on arenosols soil in Quang Binh, the paddy had the largest area (accounting for 57.1% of the area). The next position was vegetables (18.1% of the area), the next position was sweet potato (occupied 11.7% of the area) and fourth place was peanuts (accounting for 5.8% of the area). The remaining crops accounted for 1.5 to 2% of the area. Table 3.3. The structure of the annual crops area on arenosols soil in Quang Binh Order Crop Area (ha) Ratio (%) 1 Paddy 5114.7 57.1 2 Vegetables 1617.2 18.1 3 Sweet potato 1048.7 11.7 4 Peanut 515.0 5.8 5 Cassava 181.7 2.0 6 Beans 171.6 1.9 7 Corn 141.7 1.6 8 Other crops 164.8 1.8 Total 8955.4 100 3.1.2. The reality of the peanut production on arenosols soil in Quang Binh 3.1.2.1. Survey results of the peanut production from households - Scale production of the peanut production household on arenosols soil The results in Table 3.6 show: Each household had 4.5 members. The area of agricultural land/household was approximately 3,000 m2, in which about 1/5 of peanut cultivated area. The husbandry was mall-scale. 11 Table 3.6. Scale production of the household on arenosols soil Order Criteria Average value Range 1 Members/household (person) 4.51 1 - 7 2 Agricultural land/household (m2) 3,158.8 840 – 5,150 3 Paddy planted land/household (m2) 2,095.5 510 – 4,580 4 Peanut planted land/household (m2) 636.5 330 – 2,860 5 Other crops planted land/household (m2) 426.8 75 – 1,540 6 Number of buffaloes &cows/household 2.33 0 - 16 7 Number of pigs/household 5.04 0 - 45 8 Number of poultry/household 37.43 0 - 250 - Current situation of investment and scientific and technical approach in the peanut production on arenosols soil in Quang Binh Table 3.8. Investment and scientific and technical approach in the peanut production on arenosols soil in Quang Binh On the use of the varieties (%) Varieties Criteria New varieties Local varieties Percentage of households using 87.7 12.3 Self keeping of seed 48.7 100 Bought seed 51.3 0 Investment of fertilizer (kg) The level of investment by farmersCriteria Recommended level Average value Range Urea 65 60.6 45 - 65 Super phosphorous 560 407.2 350 - 500 Kaliclorua 100 115.9 70 - 120 Lime 500 439.2 300 - 500 Local manure 5,000 – 10,000 5,514 5,000 – 6,000 The scientific and technical approach in the peanut production (%) Farmers were trained Farmers were not trained 76 24 The data in Table 3.8 shows that the use of varieties was quite good and a geat deal of new varieties are put into production at a high level. Nevertheless, the fertilizer investment was not balanced and lower than the recommended process. The rate of peanut growers trained the techniques in peanut production was rather high. 12 - The structure of the peanut sowing times in winter spring season on arenosols soil in Quang Binh The results in Table 3.9 show that the sowing time frame of the farmers was quite large in the winter spring season. The production efficiency was low when unfavorable weather. Table 3.9. The peanut sowing times of the farmers in winter spring season on arenosols soil in Quang Binh Calculation unit: (%) Time Region Before of date 15/12 From 15/12 to 25/12 From 26/12 to 04/01 From 05/01 to 14/01 From 15/01 to 24/01 From 25/01 to 03/02 From 04/02 to 13/02 From 14/02 to 23/02 After of date 23/02 Le Thuy 7.8 6.4 8.6 29.0 30.3 6.2 1.7 5.4 4.6 Quang trach 0 2.4 7.0 12.2 53.1 10.4 9.3 3.2 2.4 Average 3.9 4.4 7.8 20.6 41.7 8.3 5.5 4.3 3.5 3.1.2.3. Research results of the defining nutrition restricted facts when growing peanut on arenosols soil in Quang Binh. Table 3.13. Effects of nutritional factors on the yield components and yield of peanuts on arenosols soil in Quang Binh Treatments Number of ripe pods per plant (pod) Weight of 100 pods (gram) TPY (tons/ha) RPY (tons/ha) The research implemented in Tan Tien village, Cam Thuy commune NPK (Control) 5.70a 98.67a 1.519a 1.041a Control - N 4.90a 90.33b 1.195b 0.947b Control - P 3.80c 80.33c 0.825c 0.635c Control - K 3.27c 76.67d 0.608d 0.417d LSD0,05 0.999 2.471 0.099 0.089 The research implemented in Tan Phong village, Cam Thuy commune NPK (Control) 6.57a 117.00a 1.728a 1.100a Control - N 5.40b 106.17b 1.291b 0.853b Control - P 4.07c 95.00c 0.868c 0.660c Control - K 3.47c 84.33d 0.658c 0.557d LSD0,05 0.998 3.508 0.218 0.057 Note: The different letters in the same column and studing place represent significant difference statistically at 0.05 level. 13 Research results of the yield components and yield summarized in Table 3.13 were quite similar across the two experimental sites each other. Two most obvious criteria were TPY (theoretical pod yield) and RPY (real pod yield). In which, the lowest yield of non-potassium formula, followed by non-phosphorus formula, and the highest yield of control formula. From the results we conclude the order of nutritional factors limiting peanut yields in winter spring season on arenosols soil in Quang Binh were defined as follows: K> P> N. 3.1.3. General remarks On the basis of analysis and assessment of the peanut production situation on arenosols soil in Quang Binh, in order to exploit the potential and overcome difficulties in the production need to implement multiple synchronized solutions. In which, for technical cultivation solutions should concentrate to study and apply the following techniques: balanced fertilizer and mulching soil for increasing water-holding capacity and nutrient retention of soil and reducing land erosion; along with arranging optimum sowing time; seeding density located about 40 plants/m2; use of peanut varieties have high potential of yield. That is the important technical solutions for producing peanuts on sandy soil present Quang Binh province. 3.2. Research results of the peanut fertilizer application in winter spring season on arenosols soil in Quang Binh 3.2.1. Research to determine the appropriate combination of inorganic fertilizer and manure for peanut production 3.2.1.1. Effect of the combinations on the peanut yield on arenosols soil in Quang Binh Research results summarized in Table 3.15 were quite similar across the two experimental seasons each other. Especially, there were clear differences in the TPY and RPY. Yield was highest in the VCPC11 14 combination and VCPC12 combination. There was no statistical difference between them. Table 3.15. Effects of the inorganic fertilizer and manure combinations on the peanut yield on arenosols soil in Quang Binh Treatments Number of ripe pods per plant (pod) Weight of 100 pods (gram) TPY (tons/ha) RPY (tons/ha) The research’s in the winter spring 2010-2011 in Cam Thuy commune VCPC1 4.27g 135.73e 1.738g 1.313g VCPC2 4.53g 135.73e 1.847g 1.430g VCPC3 5.47f 137.00de 2.247f 1.710f VCPC4 6.27e 140.23cd 2.635e 1.910e VCPC5 5.27f 137.63de 2.175f 1.685f VCPC6 6.73d 142.87bc 2.885d 2.120d VCPC7 7.33c 143.57abc 3.158c 2.508c VCPC8 8.13b 147.10a 3.589b 2.725b VCPC9 7.00cd 142.23c 2.987de 2.130d VCPC10 8.07b 147.10a 3.559b 2.705b VCPC11 9.6a 146.37ab 4.217a 3.010a VCPC12 9.33a 147.10a 4.118a 3.013a LSD0.05 0.465 3.554 0.211 0.131 The research’s in the winter spring 2011-2012 in Quang Xuan commune VCPC1 4.80g 132.78e 1.911g 1.355g VCPC2 5.27fg 132.75e 2.098g 1.438g VCPC3 6.53e 138.26cd 2.710e 1.873e VCPC4 7.20d 140.20bc 3.028d 2.165d VCPC5 5.67f 137.62d 2.339f 1.720f VCPC6 7.07de 140.85b 2.986d 2.248d VCPC7 8.20c 140.20bc 3.450c 2.500c VCPC8 9.07b 143.55a 3.904b 2.793b VCPC9 7.13g 140.87b 3.014d 2.278d VCPC10 9.20b 141.52ab 3.905b 2.765b VCPC11 10.20a 142.19ab 4.350a 3.113a VCPC12 10.20a 141.52ab 4.330a 3.090a LSD0.05 0.539 2.138 0.216 0.114 Note: The different letters in the same column and studing season represent significant difference statistically at 0.05 level. 15 3.2.1.2. Effects of the combinations on the economic efficiency of the peanut production on arenosols soil in Quang Binh Through calculations in Table 3.17 show: Net profit (NP) and rate of return (RR) were quite similar across the two experimental seasons each other. They were highest in the VCPC11 combination. Bảng 3.17. Effects of the combinations on the economic efficiency of the peanut production on arenosols soil in Quang Binh Calculation unit: 1000 dong/ha The winter spring 2010-2011 The winter spring 2011-2012 Treatments Income Expense NP RR Income Expense NP RR VCPC1 32825 41792 - 8967 - 36585 46792 -10207 - VCPC2 35750 44292 - 8542 - 38826 49292 -10466 - VCPC3 42750 46792 - 4042 - 50571 51792 -1221 - VCPC4 47750 49292 - 1542 - 58455 54292 4163 0,08 VCPC5 42125 43406 - 1281 - 46494 48406 -1912 - VCPC6 53000 45906 7094 0,15 60696 50906 9790 0,19 VCPC7 62700 48406 14294 0,30 67500 53406 14094 0,26 VCPC8 68125 50906 17219 0,34 75411 55906 19505 0,35 VCPC9 53250 49870 8380 0,19 61506 49870 11636 0,23 VCPC10 67625 47370 20255 0,43 74655 52370 22285 0,43 VCPC11 75250 49870 25380 0,51 84051 54870 29181 0,53 VCPC12 75325 52370 22955 0,44 83430 57370 26060 0,45 *Summary: The fertilizer combination with 40 kg N – 120 kg P2O5 – 80 kg K2O - 10 tons of farm yard manure – 500 kg lime/ha obtained both the highest yield and the highest economic efficiency 3.2.2. Research to determine the appropriate combination of inorganic and organic-microorganisms fertilizer for peanut production 3.2.2.1. Effects of the inorganic and organic-microorganisms fertilizer combinations on the peanut yield on arenosols soil in Quang Binh Research results summarized in Table 3.20 were quite similar across the two experimental seasons each other. Yield was highest in the VCVS11 16 combination and VCVS12 combination. There was no statistical difference between them. Table 3.20. Effects of the inorganic and organic-microorganisms fertilizer combinations on the peanut yield on arenosols soil in Quang Binh Treatments Number of ripe pods per plant (pod) Weight of 100 pods (gram) TPY (tons/ha) RPY (tons/ha) The research’s in the winter spring 2010-2011 in Cam Thuy commune VCVS1 4.33f 133.35e 1.733f 1.293h VCVS2 4.93de 136.37cd 2.019de 1.408g VCVS3 5.33d 135.15de 2.163d 1.708f VCVS4 5.33d 135.77de 2.173d 1.723f VCVS5 4.80e 133.35e 1.920ef 1.460g VCVS6 6.80c 137.00bcd 2.796c 1.930e VCVS7 7.67b 139.54ab 3.209b 2.355c VCVS8 7.80b 139.54ab 3.266b 2.430c VCVS9 6.73c 139.56ab 2.820c 2.090d VCVS10 7.87b 139.54ab 3.293b 2.385c VCVS11 8.80a 138.89abc 3.667a 2.628b VCVS12 8.87a 140.19a 3.729a 2.755a LSD0,05 0.437 2.629 0.203 0.077 The research’s in the winter spring 2011-2012 in Quang Xuan commune VCVS1 4.73h 132.16e 1.876g 1.340i VCVS2 5.40g 135.15d 2.190f 1.530h VCVS3 5.87f 134.53de 2.368e 1.890f VCVS4 6.07f 135.15d 2.460e 1.945f VCVS5 5.40g 135.15d 2.188f 1.773g VCVS6 7.33e 139.54bc 3.070d 2.143e VCVS7 7.93cd 140.19abc 3.336c 2.480cd VCVS8 8.27bc 140.86ab 3.492bc 2.548bc VCVS9 7.53de 138.25c 3.125d 2.388d VCVS10 8.40b 140.19abc 3.534b 2.640b VCVS11 9.27a 140.85ab 3.915a 2.860a VCVS12 9.40a 142.19a 4.009a 2.873a LSD0,05 0.428 2.409 0.177 0.094 Note: The different letters in the same column and studing season represent significant difference statistically at 0.05 level. 17 3.2.2.2. Effects of the inorganic and organic-microorganisms fertilizer combinations on the economic efficiency of the peanut production The results in Table 3.22 show: Net profit (NP) and rate of return (RR) were quite similar across the two experimental seasons each other. They were highest in the VCVS11 and VCVS12 combinations. Table 3.22. Effects of the inorganic and organic-microorganisms fertilizer combinations on the economic efficiency of the peanut production Calculation unit: 1000 dong/ha The winter spring 2010-2011 The winter spring 2011-2012 Treatments Income Expense NP RR Income Expense NP RR VCVS1 32325 41792 - 9467 - 36180 46792 -10612 - VCVS2 35200 42512 - 7312 - 41310 47512 -6202 - VCVS3 42700 43232 - 532 - 51030 48232 2798 0.06 VCVS4 43075 43952 - 877 - 52515 48952 3563 0.07 VCVS5 36500 43406 - 6906 - 47871 48406 -535 - VCVS6 48250 44126 4124 0.09 57861 49126 8735 0.18 VCVS7 58875 44846 14029 0.31 66960 49846 17114 0.34 VCVS8 60750 45566 15184 0.33 68796 50566 18230 0.36 VCVS9 44125 44870 -745 - 50625 49870 755 0.02 VCVS10 59625 45590 14035 0.31 71280 50590 20690 0.41 VCVS11 65700 46310 19390 0.42 77220 51310 25910 0.50 VCVS12 68875 47030 21845 0.46 77571 52030 25541 0.49 *Summary: The fertilizer combination with 40 kg N – 120 kg P2O5 – 80 kg K2O – 0.6 tons of organic-microorganisms fertilizer – 500 kg lime/ha obtained both the highest yield and the highest economic efficiency. 3.3. Research results of the determining the optimum planting time frame for peanut in winter spring on arenosols soil in Quang Binh 3.3.1. Effects of the planting time on the peanut yield in winter spring season on arenosols soil in Quang Binh Research results summarized in Table 3.28 were quite similar across the two experimental seasons each other. There were clear differences in the TPY and RPY. The formulae of TV3, TV4, TV5 and TV6 obtained the RPY > 1.8 tons/ha and fairly stable across the two experimental 18 seasons. For the early sowing formulae of TV1, TV2 and the late sowing formulae of TV7, TV8 had lower yield and unstable across the two experimental seasons. Table 3.28. Effects of the planting time on the peanut yield in winter spring season on arenosols soil in Quang Binh Treatments Density at harvest (plants/m2) Number of ripe pods per plant (pod) Weight of 100 pods (gram) TPY (tons/ha) RPY (tons/ha) The research’s in the winter spring 2009-2010 in Cam Thuy commune TV1 34.67 c 5.53 d 142.19 b 2.045 d 1.590 d TV2 35.33 c 6.13 c 142.86 ab 2.321 c 1.665 c TV3 36.67 b 6.67 b 142.19 b 2.607 b 1.920 b TV4 38.33 a 7.13 a 143.55 ab 2.945 a 2.170 a TV5 38.67 a 7.20 a 144.24 a 3.013 a 2.178 a TV6 38.33 a 6.60 b 140.19 c 2.660 b 1.873 b TV7 39.00 a 5.27 d 132.16 d 2.034 d 1.310 e TV8 38.67 a 4.27 e 131.01 d 1.622 e 1.265 e LSD0,05 1.289 0.338 1.955 0.162 0.066 The research’s in the winter spring 2010-2011 in Cam Thuy commune TV1 33.00 c 5.47 c 142.19 a 1.924 c 1.263 g TV2 33.33 c 5.60 c 142.88 a 2.001 c 1.303 f TV3 36.33 b 6.40 b 142.22 a 2.482 b 1.810 c TV4 37.67 ab 7.07 a 142.88 a 2.853 a 2.098 a TV5 38.00 a 7.33 a 143.57 a 3.004 a 2.110 a TV6 37.67 ab 7.20 a 141.52 ab 2.878 a 1.993 b TV7 38.00 a 6.27 b 138.25 bc 2.469 b 1.683 d TV8 37.67 ab 5.53 c 136.37 c 2.132 c 1.443 e LSD0,05 1.424 0.408 3.408 0.246 0.039 Note: The different letters in the same column and studing season represent significant difference statistically at 0.05 level. 3.3.2. Effects of the planting time on the economic efficiency of the peanut production The results in Table 3.29 show: Net profit (NP) was quite similar across the two experimental seasons each other. The peanut production of the early sowing TV1, TV2 formulae and the late sowing TV7, TV8 formulae were loss. 19 Table 3.29. Effects of the planting time on the economic efficiency of the peanut production on arenosols soil in Quang Binh Calculation unit: 1000 dong/ha The winter spring 2010-2011 The winter spring 2011-2012 Treatments Income Expense NP Income Expense NP TV1 31800 36280 - 4480 31575 46826 -15251 TV2 32300 36154 - 3854 32575 46583 -14008 TV3 38400 34992 3408 45250 45037 213 TV4 43400 34076 9324 52450 43720 8730 TV5 43560 34160 9400 52750 42960 9790 TV6 37460 34117 3343 49825 42777 7048 TV7 26200 34096 - 7896 42075 42868 -793 TV8 25300 34136 - 8836 36075 42746 - 6671 *Summary: The optimum planting time frame of the peanut production in the winter spring on arenosols soil of Quang Binh province was defined from date 04/01 to date 03/02. 3.4. Research results of the soil mulching application for peanut production in winter spring on arenosols soil in Quang Binh 3.4.1. Effects of the soil mulching materials on the peanut yield in winter spring on arenosols soil in Quang Binh Table 3.33. Effects of the soil mulching materials on the peanut yield in the winter spring 2011-2012 on arenosols soil in Quang Binh Treasments Number of ripe pods per plant (pod) Weight of 100 pods (gram) TPY (tons/ha) RPY (tons/ha) The research’s in Cam Thuy commune, Le Thuy district No mulch (Control) 6,53b 142,19b 2,786c 2,180c Plastic mulch 7,53a 148,52a 3,356b 2,575b Straw mulch 8,00a 147,08a 3,529a 2,680a LSD0,05 0,478 3,883 0,168 0,036 The research’s in Quang Xuan commune, Quang Trach district No mulch (Control) 6,67b 140,86b 2,816b 2,198b Plastic mulch 7,80a 147,08a 3,441a 2,653a Straw mulch 8,00a 146,37ab 3,513a 2,655a LSD0,05 0,684 9,325 0,226 0,096 Note: The different letters in the same column and studing place represent significant difference statistically at 0.05 level. 20 The results in Table 3.33 show: Effects of the soil mulching materials on the yield components and yield of peanuts in two experimental places were quite clear. The formulas of the soil mulching application had TPY and RPY significantly higher with control formula 0.35 to 0.5 tons/ha. Comparison of the plastic mulch formula and the straw mulch formula, the criteria were not significant difference in the experiment at Quang Xuan, and in the experiment at Cam Thuy the criteria of the straw mulch formula were significant higher than the plastic mulch formula, but not much. 3.4.2. Effects of soil mulching materials on the economic efficiency of the peanut production Bảng 3.37. Effects of soil mulching materials on the economic efficiency of the peanut production on arenosols soil in Quang Binh Calculation unit: 1000 dong/ha Experiment in Cam Thuy Experiment in Quang Xuan Treasments Income Expense NP RR Income Expense NP RR No mulch (Control) 58860 50906 7954 0,16 59346 50906 8440 0,17 Plastic mulch 69525 53606 15919 0,30 71631 53606 18025 0,34 Straw mulch 72360 53906 18454 0,34 71685 53906 17779 0,33 The results in Table 3.37 show: Net profit (NP) was quite similar across the two experimental places each other. The net profits were the highest of the straw mulch formula, followed by the plastic mulch formula and the lowest of control formula. The NP of the soil mulching application formulae was much higher than the control treatment (15.919 to 18.454 million dong/ha). RR of the mulching application formulae gained high (0.3 – 0.34). *Summary: The results showed that the use of covering materials increased pod yield, economic efficiency and the fertility of the soil higher than with no cover. In terms of agricultural production on arenosols soil in Quang Binh province today, the application of covering soil with straw was suitable and has many advantages than covering soil with plastic in peanut production. 21 3.5. The results of building the peanut production demonstration in the winter spring 2012-2013 on arenosols soil in Quang Binh 3.5.1. The yield of the peanut production demonstration in the winter spring 2012-2013 on arenosols soil in Quang Binh Bảng 3.38. The yield of the peanut production demonstration in the winter spring 2012-2013 on arenosols soil in Quang Binh Combination 2 Combination 3 Criteria C om bination 1 (C ontrol) A verage value C om pared w ith the control (% ) A verage value C om pared w ith the control (% ) Density at harvest (plants/m2) 36.4 37.9 + 4.2 38.0 + 4.4 Number of pods/plant (pod) 7.49 12.31 + 64.2 10.69 + 42.7 Weight of 100 pods (gram) 141.5 153.1 + 8.2 147.1 + 3.9 Weight of 100 seeds (gram) 62.1 65.2 + 5.2 63.9 + 2.9 Theoretical pod yield (tons/ha) 2.895 5.360 + 85.1 4.483 + 54.9 Real pod yield (tons/ha) 2.095 3.743 + 78.6 3.335 + 59.2 The results in Table 3.37 show: The criteria of the combined new techniques application in two combinations 2 and 3 were clearly higher than the control combination. RPY (Real pod yield) was the clearest, the highest of the combination 2 (78.6% higher compared to the control) and followed by combination 3 (higher than 59.2% compared to control) 3.5.2. The economic efficiency of the peanut production demonstration in the winter spring 2012-2013 on arenosols soil in Quang Binh Table 3.39. The economic efficiency of the peanut production demonstration on arenosols soil in Quang Binh (calculated for 1 ha) Calculation unit: 1000 dong/ha Criteria Combination 1 (Control) Combination 2 Combination 3 Expense 48,426 54,170 51,210 Income 56,619 101,061 90,045 Net profit (NP) 8,193 46,891 38,835 Rate of Return (RR) 0.17 0.87 0.76 22 The results of economic efficiency in Table 3.39 show: Although the investment cost of the combinations 2 and 3 were higher than the control combination, however, NP obtained a much higher (5-6 times compared with the control combination). In particular, when considering RR showed the effectiveness of capital investments in the two combinations 2 and 3 (reaching 0.76 to 0.87) greater than the control combination (reaching 0.17). For the two combinations 2 and 3, the economic efficiency of the combination 2 was higher than the combination 3. *Summary: The results of the the peanut production demonstration applied new techniques in large-scale had achieved the target of the research: Yield from 2.097 tons/ha increased up to 3.335 - 3.743 tons/ha; Profit from 8.193 million/ha increased up to 38.835 - 46.891 million/ha; RR (rate of return) from 0.17 increased up to 0.76 - 0.87. CONCLUSIONS AND RECOMMENDATIONS 1. Conclusions 1.1. Examining current peanut production and assessing factors restricting peanut yield on arenosols soil in Quang Binh: The peanut has an important role in the structure of annual crops on arenosols soil due to high adaptability to the production conditions. The area's arenosols soil for peanut production is quite large (around 5,500 ha). Farmers trained technical knowledge of peanut production accounts for a high proportion (76%). New peanut varieties are also used with high percentage (87.7%). Farmers were fully aware of the problems in peanut production and knew a number of methods to solve them. However, yield 23 and economic efficiency of peanut production on this soil type still reached a low level because of the restricting factors as follows: - The arenosols soil has low natural fertility. Most of the nutritional elements needed for peanut growth and development are being very poor. Moreover, experimental results show that K and P are the two leading nutrient factors which cause restricting peanut yield. Meanwhile, the farmers' fertilizer was arbitrary because there is no fertilizer process for peanut production on arenosols soil of Quang Binh. - Because conditions in which the weather occurs abnormally, the peanut production based totally on the rainfed and no study on peanut planting time on the coastal lands, the Quang Binh Service of Agriculture and Rural Development has instructed farmers peanut planting time frame in winter spring season from 15/12 to 25/02. The period of time like that is too large and one of the basic causes of low yield and economic efficiency of peanut production. 1.2. Identifying inorganic and organic fertilizer combinations for peanut production on arenosols soil in Quang Binh province is the highest yield and economic efficiency. That are the first combination of 40 kg N - 120 kg P2O5 - 80 kg K2O - 500 kg lime - 10 tons manure/ha and the second combination of 40 kg N - 120 kg P2O5 - 80 kg K2O - 500 kg lime – 0,6 tons organic- microorganisms fertilizer/ha. Applying the first combination, pod yield increased from 3.1 to 3.113 tons/ha, net profit increased from 25.38 to 29.18 million/ha, rate of return increased from 0.51 to 0.53; while applying the second combination, pod yield increased from 2.628 to 2.68 tons/ha, net profit increased from 19.39 to 25.91 million/ha, rate of return (RR) increased from 0.42 to 0.5. 1.3. The optimum planting time frame for peanut production in winter spring season on arenosols soil in Quang Binh is from date 04/01 to date 03/02. 24 During this time frame, real pod yield of peanut reached 1.81 to 2.178 tons/ha and ensure the economic efficiency of peanut production. 1.4. The use of soil mulching materials for peanut production in winter spring sseason on arenosols soil in Quang Binh was meant to increase more yield, economic efficiency and improved soil physical and chemical characteristics than no mulch. The soil mulching treatments increased more 0.395 - 0.482 tons/ha of pod yield, 7.966 - 10.01 million/ha of net profit and 0.14 - 0.17 of RR (rate of return) than no cover. Comparing two kind of materials, straw mulch is more suitable than mulch plastic in peanut production, because of both reducing production cost due to advantage of the available straw resources, and to improve soil fertility. 1.5. Applying integrated technical methods defined by this research were more outstanding results in terms of yield and economic efficiency than the traditional cultivation. Real pod yield increased 59 - 79% (from 2.95 tons/ha went up 3.335 - 3.743 tons/ha); net profit (NP) increased from 8.19 million/ha to 38.83 - 46.89 million/ha and rate of return (RR) increased from 0.17 to 0.76 - 0.87. 2. Recommendations 2.1. Application of the integrated technical cultivation measures which our research had identified in order to increase yield and economic efficiency in peanut production on arenosols soil of Quang Binh province. This is the basis for encouraging the expansion of peanut acreage and exploiting the potential of this land. 2.2. Use of organic fertilizer in peanut production on arenosols soil is an important requirement to keep and ensure stable production. Therefore, it is necessary to encourage the production of organic fertilizers from animal waste, peat, agricultural residues, .... PUBLISHED SCIENTIFIC PAPERS RELATED TO THE THESIS 4. Nguyen Minh Hieu, Le Thanh Bon, Ho Khac Minh (2011), The potentials and challenges for developing groundnut in Quang Binh coastal sandy land, Vietnamese Science and Technology Journal of Agriculture & Rural Development, 7, pp. 3 – 7. 5. Ho Khac Minh, Nguyen Minh Hieu (2012), Effects of planting time on growth and yield of the groundnut variety L14 in winter spring seasons on arenosols soil of Quang Binh province, Vietnamese Science and Technology Journal of Agriculture & Rural Development, 10, pp. 12 – 20. 6. Le Thanh Bon, Ho Khac Minh (2012), Effects of fertilizer combination on yield of the groundnut variety L14 on arenosols soil of Quang Binh province, Vietnamese Science and Technology Journal of Agriculture & Rural Development, 10, pp. 59 – 67.