Evaluation of Rock Phosphate Enriched Compost on Soil Nutrient Status after Harvest of Finger Millet-Cowpea Cropping Sequence in High Phosphorus Soils of Cauvery Command Area, Karnataka

A field experiment was conducted at Zonal Agricultural Research Station, VC Farm, Mandya during kharif 2017, summer 2018, kharif 2018 and summer 2019 to study the effect of rock phosphate enriched compost on soil nutrient status after harvest of finger millet-cowpea cropping sequence. Prior to initiation of the field experiment, three different composts viz., urban solid waste compost (USWC), vermicompost and farm yard manure (FYM) were enriched with rock phosphate at 5 per cent. Field experiment consisting of eleven treatment combinations comprising recommended N and K, and P through varied levels of enriched composts. The experiment was laid out in RCBD design with three replications and the test crops were finger millet and cowpea. The initial P2O5 of the experimental site was very high (133.58 kg ha-1). The results revealed that application of recommended N and K + 75 per cent P supplied through enriched USWC (T5) had significantly higher organic carbon (0.56 and 0.58%) in pooled data of both finger millet and cowpea, respectively. Available N (241.94 and 224.86 kg ha-1), P2O5 (138.69 and 120.99 kg ha-1) and K2O (153.92 and 135.31 kg ha-1) were recorded significantly higher in T5 of finger millet and cowpea, respectively. Similarly, in pooled mean, exchangeable Ca [4.15 and 4.04 C mol (P+) kg-1] and Mg [2.16 and 2.05 C mol (P+) kg-1] were recorded significantly higher in treatment which received recommended N and K + 75 per cent P supplied through enriched vermicompost (T8) in both finger millet and cowpea, respectively. The decrease of available P2O5 was 20.98 per cent from initial (133.58 kg ha-1) to final crop (summer 2019) (105.55 kg ha-1).

Different Adaptive Strategies of Three Mangrove Species to Nutrient Enrichment: Revealed by Trait-based Analysis

Mangrove species are undergoing environmental changes from nutrient-poor to nutrient enrichment due to the large input of external nutrients. The potential difference in adaptive strategies between the slow- and fast-growing species may lead to great changes in species interaction and ecosystem functioning. This study aims to test whether the response strategies to soil nutrient availability differ between the slow- and fast-growing mangrove species. The comparison was carried out among three common mangrove species including two slow-growing species Aegiceras corniculata and Kandelia obovata, and one intrinsic fast-growing species Laguncularia racemosa. All tested species showed conservative strategies (such as slow-growing and high concentrations of leaf tolerance/resistance traits) when living in the nutrient-poor soils. But when soil nutrient increased, L. racemosa shifted to a fast-growing strategy, accompanied by a substantial reduction of tolerance traits including the concentrations of carbon, cellulose, total phenolics, and soluble sugar in leaves. In contrast, A. corniculatum and K. obovata maintained still conservative strategies even under nutrient enrichment. All the species increased leaf nitrogen, phosphorus, lipid, lignin and specific leaf area (SLA) with soil nutrient availability, but L. racemosa showed a greater nutrient acquisition capacity indicated by a steeper regression line of SLA vs. nutrient resorption efficiency than A. corniculatum. Further, the steeper regression line of SLA vs. leaf δ13C of L. racemosa indicated a higher water use efficiency than A. corniculatum. The dependence of the adaptive strategies of these species to soil nutrient status improved the standing of plant-plant interactions at different soil nutrient status.

Effect of Organic and Inorganic Sources of Nitrogen on Yield, Microbial Load and Soil Nutrient Status of Pearl Millet

Soil microbial population and soil nutrient status are important criteria for improving the yields. So this study is conducted with an objective to know the impact of organic and inorganic sources of nitrogen on yield, soil microbial load and nutrient status of the soil in pearl millet. A field experiment was conducted during kharif, 2019 at Agricultural College Farm, Bapatla on sandy soils with eight treatments consisting combined organic and inorganic nitrogen sources. The highest grain yield (2955 kg ha-1), straw (5867 kg ha-1) yield and soil nitrogen status (164.10 kg ha -1) were recorded with 75% Soil Test Based Nitrogen (STBN) + 25% vermicompost + Azospirillum @ 5 kg ha-1 and was followed by statistically similar treatment 100% STBN + Azospirillum @ 5 kg ha-1. Significantly higher microbial load (Bacteria, Fungi and Actinomycetes), P and K status in soil recorded with the treatments where 50% of STBN applied through FYM (50% STBN + 50% FYM + Azospirillum @ 5 kg ha-1), whereas lowest was recorded with chemical fertilizer alone. The combined sources of nitrogen both organic and inorganic fertilizers would be able to improve soil fertility and soil microbial load and finally improve the yields.

Effects of Organic Manures and Green Manuring on Growth, Yield, Economics and Quality of Lemongrass (Cymbopogon Flexuosus L.) In Custard Apple (Annona Squamosa L.) Based Agri-Horti System

A field experiment was conducted to explore the effects of organic manures and green manuring practices on growth, yield attributes, quality and economics of lemongrass (Cymbopogon flexuosus L.) under custard apple (Annona squamosa L.) based agri-horti system. The findings indicated that growth, yield attributes and yield as well as oil composition, soil nutrient status, microbial populations were significantly increased due to the use of both organic manures and green manuring. The significantly higher results were obtained with vermicompost (2.5 t/ha) + Azotobacter, which was found superior over other practices in terms of growth, yield attributes, oil composition and its quality and soil nutrient status as well as economics of crop cultivation. Bangladesh J. Bot. 50(3): 499-506, 2021 (September)

Short-term impacts of winter bale grazing beef cows on forage production and soil nutrient status in the eastern Canadian prairies

The impact of winter bale grazing on forage productivity and nutrient cycling was determined near Winnipeg, MB. Variable distribution of nutrients and forage yield within bale grazed plots on a perennial grass-legume forage field was identified using an intensive grid sampling method. In bale-grazed plots, mean dry matter (DM) yield of forage decreased 68% in year one following bale grazing, with no difference in DM yield in year two following bale grazing, relative to an untreated control. Decreased yield was attributed to the large mass of waste feed and feces (21% of feed delivered) that remained at the centre of each bale-grazed plot, where each bale was placed. Concentrations of crude protein, total digestible nutrients, phosphorus (P), and potassium in forage increased in the first growing season following winter bale grazing compared to the control, particularly at the centre of each bale-grazed plot. Concentrations of residual nitrate-nitrogen and Olsen P in soil were 15 and 2.5 times greater, respectively, at the centre of the bale-grazed plots compared to untreated control plots. Dispersion of waste feed packs when bale grazing in sub-humid climates on clay soils is recommended to minimize smothering and encourage rapid decomposition of waste feed and feces. Long-term studies are needed to determine the potential benefits and risks of bale grazing to forage productivity and soil nutrient status in the eastern Canadian prairies.