ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Potassium Status and Physicochemical and Mineralogical Properties of Lowland Vertisols in a Rice-Based Cropping System under Tropical Savanna Climate)

ผู้เขียน:Kyaw Ngwe, นายเอิบ เขียวรื่นรมณ์, ศาสตราจารย์เกียรติคุณ, นางสาวอัญชลี สุทธิประการ, ศาสตราจารย์เกียรติคุณ

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Abstract

Five profi les of lowland Vertisols—namely, Ban Mi (Bm1, Bm2), Chong Khae (Ck), Lop Buri (Lb) and Wattana (Wa) series— which are typical rice growing soils under tropical savanna climate developed on local alluvium derived from limestone were sampled according to the genetic horizon and studied with the objectives to determine various forms of soil K and to establish the relationships between different forms of K and their soil properties. These soils were slightly alkaline to strongly alkaline and all soils had a clayey texture. Smectite and interstratifi ed kaolinite-smectite dominated their clay fractions with lesser amounts of kaolinite and illite. NH4OAc-exchangeable K of these soils ranged between 19.32 and 130.53 mg kg-1 with an average value of 42.71 mg kg-1. For K fertility status, the topsoil of Bm1 had a “very high” content of available K. The content of available K in the topsoil was observed from high to low in the order Bm1 > Ck > Wa > Lb > Bm2. Non-exchangeable K is potentially available to plants in direct dynamic equilibrium with the exchangeable K form. The non-exchangeable K content of Ck was highest and was lowest in Lb in both the topsoil and subsoil. HNO3-extractable K was very highly signifi cantly correlated with non-exchangeable K (r = 0.995) and signifi cantly correlated with NH4OAc-exchangeable K (r = 0.472) and total K (r = 0.466). The organic matter content was highly signifi cantly correlated with NH4OAcexchangeable K (r = 0.554). Non-exchangeable K was very highly signifi cantly correlated with HNO3 extractable K (r = 0.994) and total K (r = 0.961). The results revealed that different forms of potassium along with organic matter maintenance should be critically considered for management of potassium fertility in these soils for rice-based cropping practice.

Article Info

Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 046, Issue 4, Jul 12 - Aug 12, Page 522 - 537 |  PDF |  Page

ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Development of a Vegetable IPM Program in a Rice-Based Cropping System)

ผู้เขียน:T.M. Aganon, M.G. Patricio, J.I. Calderon, Soriano Jr, M. L. J. Sison

สื่อสิ่งพิมพ์:pdf

Abstract

The study was conducted with the objective of developing a pest management scheme in vegetables that is compatible with the principles of IPM. The first stage of the study was the mapping of the arthropod population profile in the two crops under study (stringbeans and eggplant). Eight insect pests were recorded on stringbeans with five criticial windows. In eggplant, leafhopper, thrips, and fruit and shoot borer predominated and five critical windows were also observed. The profile was used as the basis for identifying critical stages when the crops were most susceptible to pest damage and in formulating corrective measures or pest management intervention. The second stage was a field comparison of farmers' pest management practices with strategically timed insecticide applications. Field trial results in the two vegetable crops showed that strategic insecticide applications outperformed farmers' practice by producing higher yields, requiring fewer sprays, lowering production cost, and incurring higher profits or ROI. The strategy optimized the effect of insecticides on the pests while minimizing the impact on beneficial arthropods. Further studies are presently being conducted which include insecticide x parasitoid complementation. Initial trials showed promising results.

Article Info

Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 032, Issue 5, Jan 98 - Dec 98, Page 32 - 36 |  PDF |  Page