Biofertilizers are becoming increasingly popular in many countries and for many crops, but very few studies on their effect on grain yield have been conducted in rice. Therefore, we evaluated three different biofertilizers (based on Azospirillum, Trichoderma, or unidentified rhizobacteria) in the Philippines during four cropping seasons between 2009 and 2011, using four different fertilizer rates (100% of the recommended rate [RR], 50% RR, 25% RR, and no fertilizer as Control). The experiments were conducted under fully irrigated conditions in a typical lowland rice environment. Significant yield increases due to biofertilizer use were observed in all experimental seasons with the exception of the 2008/09 DS. However, the effect on rice grain yield varied between biofertilizers, seasons, and fertilizer treatments. In relative terms, the seasonal yield increase across fertilizer treatments was between 5% and 18% for the best biofertilizer (Azospirillum-based), but went up to 24% in individual treatments. Absolute grain yield increases due to biofertilizer were usually below 0.5 t·ha−1, corresponding to an estimated additional N uptake of less than 7.5 kg N ha−1. The biofertilizer effect on yield did not significantly interact with the inorganic fertilizer rate used but the best effects on grain yield were achieved at low to medium fertilizer rates. Nevertheless, positive effects of the biofertilizers even occurred at grain yields up to 5 t·ha−1. However, the trends in our results seem to indicate that biofertilizers might be most helpful in rainfed environments with limited inorganic fertilizer input. However, for use in these target environments, biofertilizers need to be evaluated under conditions with abiotic stresses typical of such systems such as drought, soil acidity, or low soil fertility

: Kepulauan Bangka Belitung, Indonesia is one of the tin mineral-producer in the world.Agricultural crops could be a wise option for the reclamation since abandoned tin-mining lands have a high potency to be used as agricultural lands. This study was aimed to evaluate of the land/soil characteristics of abandoned tin-mining areas and to establish land suitability of the land area for agriculture used to formulate appropriate land development measures and amelioration strategies forutilization of mined areas for crop production. The land evaluation was conducted by comparing the land characteristics in every type of abandoned tin-mining areas with its crop requirements. The current suitability showed that in general food crops, vegetable crops, fruit crops, and industrial crops were consider as not suitable (N). Spice and medicinal crops [pepper (Piper nigrum L.)] and citronella (Andropogoh nardus L. Rendle)] were consider as not suitable (N), while the Jatropha (Jatropha curcas L.) and Kemiri Sunan (Aleurites moluccana L. Willd) crops were considered as marginally suitable (S3) in abandoned tin-mining areas. The forest crops and forage crops were considered as marginally suitable (S3). The water availability, soil texture, and low soil fertility were considered as the limiting factors of all crops to get optimum production. For agricultural development, the soil physical and chemical properties of abandoned tin-mining land must be improved through integrated farming.

Industrialization, urbanization and intensive use of farm inputs can pollute agricultural areas. The study was then conducted to assess the levels of chromium (Cr), nickel (Ni), copper (Cu), cobalt (Co), zinc (Zn), arsenic (As), molybdenum (Mo), cadmium (Cd), mercury (Hg), and lead (Pb) in the country’s major rice areas. The study also determined the contributions of soil properties, land uses, irrigation water, and farm inputs to the metal levels. Strategic collections of soil, plant and water samples in the country’s major soil series planted to rice, analyses of samples using x-ray fluorescence or atomic absorption spectroscopy, and farmer interviews were done. Metal levels were very high in Zambales and Negros Occidental soils due to deposition or use of metal-enriched mine tailings and irrigation water. Soil metal concentrations in Zambales far exceeded the intervention values of 180 mg/kg for Cr and 100 mg/kg for Ni. Soil metal levels in Negros Occidental exceeded the intervention value of 190 mg/kg for Cu and Mo. Rice plants in Negros Occidental exceeded the toxic levels of 30 mg/kg for Cu and 10-50 mg/kg for Mo due to the very high soil Cu and Mo concentrations in the area. Molybdenum concentrations of rice plants in Sultan Kudarat and Camarines Sur exceeded the toxic level due to the high amounts of foliar chemicals applied at >66 sprayer loads per year. The study implies that rice areas deposited with mine wastes have high heavy metal levels, and foliar chemicals can increase metal levels in rice.   Keywords - Environmental toxicology, heavy metals, heavy metal sources, rice soils, Philippines

Nutrient levels in rice areas can be translated to the soils' capacity to supply the essential elements for rice, while information about nutrient sources can be used to formulate management options to areas deficient or toxic in nutrients. This study was then conducted to assess the potassium (K), calcium (Ca), sulfur (S), iron (Fe) and manganese (Mn) levels in the Philippines' major rice areas. The study also determined the contributions of soil properties, land uses, irrigation water, and farm practices to the nutrient levels. Strategic collection of soil and plant samples, laboratory analyses of samples, and farmer interviews were done. Potassium concentrations of rice plants in La Paz (Tarlac) and Sta. Rosa City (Laguna) exceeded the toxic concentration of 3%. These K concentrations can be due to the increase of the nutrient's availability owing to the neutral soil pH levels in the two sites. The highest total Ca levels were found in the Polangui (Albay), La Paz, and Villasis (Pangasinan) soils. These Ca levels can be ascribed to the occurrence of Ca in sand and silt-sized soil fractions. Total Fe and Mn concentrations were very high in the Sta. Cruz (Zambales) soil due to the input of mine wastes. The San Leonardo (Nueva Ecija) soil's high total Fe concentration is probably due to the occurrence of Fe in clay-sized soil fractions. Iron and Mn levels of rice in most Central Luzon sites exceeded the toxic concentrations of 1000 mg kg-1 for Fe and 300 mg kg-1 for Mn. These concentrations can be due to the high total soil Fe and Mn levels, and their increased plant uptake due to periodic soil submergence and increased soil acidity from continuous cropping. The study implies that K, Ca, Fe and Mn are enriched in rice areas due to soil properties and farm practices.

This study was conducted to provide baseline data on the agroecosystem characteristics needed by the development planners and policymakers specifically for under-utilized and neglected crops, such as abaca, at the east-central portion of the Philippine archipelago. The results revealed that the most common companion crops for abaca were anii ( Erythrina fusca), narra ( Pterocarpus indicus), coconut, fruit trees, and other forest trees. Among the areas sampled, biomass and fiber yield performance of abaca ranges from 200 kg/ha to 1,200 kg/ha, which is far below the potential and attainable yield. These areas were located along the central mountain range of the island (i.e., Leyte Cordillera). The main consumers of the produced raw fiber were the two pulping plants in the province, which can be considered as an advantage to those farms that are located nearest to it. Among the areas surveyed, soil samples had loam texture that ranged from sandy loam to clay loam and were slightly acidic, with pH of 4. 44-6.38. Samples in the mountain area of Ormoc city (i.e., Site No. 03) showed the lowest pH, higher percentage of organic carbon, and lower extractable phosphorus. However, among the areas surveyed, more than three-fourths had higher exchangeable bases that resulted to higher cation exchange capacity values.