Reintroduction of a native Glomus to a tropical Ultisol promoted grain yield in maize after fallow and restored the density of arbuscular mycorrhizal fungal spores

Maize (Zea mays L.) is an important crop in central Thailand where fallow is widely practiced and farmers are interested in crop rotation and beneficial soil biota. A pot experiment using a Typic Paleustult (topsoil + subsoil) from the National Corn and Sorghum Research Centre, Nakhonratchasima Province, Thailand was undertaken over three successive crops to evaluate effects of agronomic practices on populations of arbuscular mycorrhizal (AM) fungi and to determine whether reintroduction of a local Glomus was beneficial to maintain maize yield. The three crops and their treatments were: (1) preceding crop: maize grown in all pots; (2) subexperiment 1: agronomic practices [maize, fallow +/- soil disturbance, fallow with solarization, non-AM host (cabbage)]; and (3) subexperiment 2: maize +/- Glomus sp. 3 at three rates of P fertilization (0, 33, 92 kg P ha(-1)). The AM-fungal community was established under the preceding crop. In subexperiment 1, the three fallow treatments decreased (30%-40%) the total AM spore number in the topsoil whereas there was no change under maize or cabbage. Glomus, the dominant genus, showed sensitivity to fallow. In subexperiment 2, inoculation with Glomus sp. 3 enhanced total AM spore number and root colonization when applied following the three fallow treatments. Furthermore, inoculation promoted grain yield; at nil P following fallow +/- soil disturbance, at 33 kg P ha(-1) following fallow without soil disturbance, and following solarization. Two treatments, maize following maize and maize following cabbage, did not respond to inoculation with Glomus sp. 3. Overall, the results suggest that reintroduction of Glomus sp. 3, a local AM fungus in this soil, may overcome negative effects of fallow and promote effectiveness of P fertilizer. Further work is needed to evaluate the benefits of other indigenous AM species that persist under modern fertilization practices

Production of Soy Sauce Koji Mold Spore Inoculum in Plastic Bags

An innovation is described for producing soy sauce koji mold spore inoculum by using inexpensive autoclavable plastic bags and reuseable plastic enclosures to make culture vessels. After growth, the spore mass could be dried and packaged in the same bag after removing the enclosure. Broken rice was used as the substrate for mold cultivation. Viable spore counts of 10(9) spores per g were obtained under optimal conditions. After drying at 50°C for 6 h, the moisture content of the spore mass decreased from 35.22 to 6.32% with no significant effect on spore viability. The dry spores could be stored in the refrigerator or at room temperature for at least 3 months

Equations for Calculating N-Fertilizer Rates for Khaw Dauk Mali-105 Rice from Soil Analysis

ABSTRACT Comparisons were made to assess the reliability of 10 chemical methods for evaluating the availability of N in soils to Khaw Dauk Mali-105 rice and for calculating rates of N-fertilizer for rice. The methods studied were: (1) measuring soil organic matter by Walkley and Black's method, (2) measuring total soil N by Kjeldahl's method, (3) extracting soil N with acidified K 2 Cr 2 O 7 solution, (4) extracting soil N with basified KMnO 4 solution, (5) extracting soil N with acidified KMnO 4 solution, (6) extracting soil N with solution of CaCl 2 and K 2 SO 4 , (7) extracting soil nitrate according to Only the indices from the methods (9) and (10) gave significant relationships (at 95% confidence level) with the relative paddy yields, with Method (10) showing slight superiority over the method (9). None of the chemical methods gave significant relationships among the index and the relative dry matter and amount of N in plants. The equations for calculating rates of N fertilizer required for desired paddy yields were: (a) log (100 -y) = 2 -0.0226b -0.0374x for method (9) and (b) log (100-y) = 2 -0.00533b -0.0584x for method (10); where y is the desired grain yield (as % of maximum yield), b availability index value for soil N (in ppm N), and x rate of fertilizer N required (as kg N/rai, 6.25 rais = 1 ha). Both of the two equations gave highly significant correlation between the actual paddy yields and the predicted paddy yields. However, method (10) was more recommended than method (9) for it was more reliable than method (9) in prediction of the yield