Litterfall and Element Return in an Abies faxoniana Forest in Tibet—A Five-Year Study

Forest litter is the main contributor to soil fertility and the main carrier of circulating material and energy in forest ecosystems. Abies faxoniana (Minjiang fir) is one of the dominant species in alpine forest ecosystems. Its litter input plays important roles in soil organic matter formation and biogeochemical cycles in these ecosystems, but the annual litterfall pattern and its components remain largely unknown. To determine the litter input and nutrient return of A. faxoniana, we measured the litterfall and element (carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), aluminium (Al), iron (Fe), and manganese (Mn)) contents of different litter components (branches, leaves and epiphytes) from 2016 to 2020. The results showed that the annual litterfall in the A. faxoniana forest ranged from 2055.96 to 5384.15 kg·ha−1·a−1, and the average mass proportions of branches, leaves and epiphytes were 30.12%, 62.18% and 7.7%, respectively. The litterfall yield varied significantly with time and component; not only was the yield of litter in the nongrowing season higher than that in the growing season, but it also exhibited dramatic interannual variations. We also found that time had significant effects on the contents of all elements except for Ca in the litter. The return and input amounts of each element followed the same dynamics, which closely resembled a bimodal pattern. Moreover, there was significant interannual variability in the returned amounts of each element. The ranges of annual returns of C, N and P were 744.80~2275.12, 19.80~59.00 and 1.03~2.81 kg·ha−1·a−1, respectively. The ranges of annual returns of K, Ca, Na, Mg, Al, Fe and Mn were 0.91~2.00, 7.04~18.88, 0.13~0.58, 0.33~1.20, 0.55~2.29, 0.41~1.37 and 0.16~0.48 kg·ha−1·a−1, respectively, reflecting a seasonal double-peak pattern. These results have important implications for understanding the biogeochemical cycles and material migration processes in alpine forest ecosystems.

IMPROVING THE PROCESS OF AMMOPHOS PRODUCTION IN THE CONDITIONS OF VIBROGRANU¬LATION

The market of mineral fertilizers is developing rapidly, which contributed to the growth of agricultural production in general and the growth of demand in the world market in particular. As a result, the supply of mineral fertilizers on the market, which is formed due to its own production and import of products, grew. Chemical companies, taking into account the current situation, have shifted from the insolvent domestic market to the world market, as a result of which this segment has provided, along with the metallurgical industry, a significant share of foreign exchange earnings over the past decade. Mineral fertilizers are an important source of nutrient return to the soil and the basis for modern modern technologies and profitable agribusiness. In recent years, Ukraine has seen an increase in the use of basic types of mineral fertilizers, as well as an increase in the application of complex fertilizers. Demand for fertilizers in Ukraine is formed by farms of various organizational and legal forms and sizes of land use, including large agricultural holdings, where considerable attention is paid to the intensification of agricultural production. In the usual technological mode, the neutralization of phosphoric acid in the apparatus of the high-speed evaporator-evaporator (SAV) is carried out with liquid ammonia. Liquid ammonia in the SAV apparatus first evaporates, and then gaseous ammonia reacts with phosphoric acid. The neutralization process results in a low-concentration ammophos pulp. It is established in the work that during the research of ammophos production in the conditions of vibrogranulation the technological process is improved due to the installation of more optimal nozzles of the BGS apparatus. The characteristics of raw materials, finished product and auxiliary materials are analyzed; physico-chemical bases of the process. Selected technical characteristics of the main and auxiliary equipment. According to the results of the research, it is proposed to install a transport nozzle, to improve the optimal conditions of the technological process, structural elements of the main devices.

Leaf Litter Production and Nutrient Return in Coffee (Coffea canephora) Plantations of Different Ages in Ibadan, Nigeria

This study investigates the role of leaf litter and its nutrient input on soil fertility levels in coffee plantations of different ages in Ibadan, Nigeria. Four coffee plantations of 11, 19, 24 and 51 years were selected for the study. Each plantation was divided into four blocks where leaf litter, soil and plant samples were collected and analyzed for nutrient .Results indicated that mean total leaf litter input in these plantations ranged from 2.50 - 3.5 tha-1yr-1 with a minimum in the 11 year old plantation and maximum in the 51 year plantation. Nitrogen input from leaf litter across the coffee plantations ranged from 27.60 – 60.07 kgNha-1year-1, which was insufficient to meet the nitrogen need of coffee trees. This was reflected by the low nitrogen content of soils of the coffee plantation (0.2 g/kg - 0.8 g/kg) which was below the soil critical nitrogen level of 0.9 g/kg recommended for coffee production. Phosphorus input from the leaf litter in the different plantations was also low 0.38 - 1.73 kgPha-1 as evident from the low phosphorus content of the soil 4.49 - 5.94 mg/kg. This was also reflected in the low leaf phosphorus content of 0.14 - 0.23 g/kg. The potassium content of the leaf litter was also insufficient 17- 55.8 kg Kha-1. Calcium, magnesium, iron, and zinc were sufficient. Coffee leaf litter contributes considerable amount of nutrient to natural soil fertility management of coffee plantations but this is inadequate to meet the nutrient requirement of coffee. There is therefore need for application of fertilizer to supply limiting nutrients.

Effects of defoliation timing on plant nutrient resorption and hay production in a semi-arid steppe

Aims Nutrient resorption is a key plant nutrient conservation strategy, and its response to environmental and management changes is linked to nutrient cycling and production of ecosystems. Defoliation is a major pathway of mowing affecting plant nutrient resorption and production in grasslands, while the effect of defoliation timing has not been unexplored. The aim of this study was to examine the effect of defoliation timing on plant nutrient resorption and production in a steppe ecosystem. Methods We conducted a field experiment in a semi-arid steppe of Inner Mongolia including four treatments: early defoliation, peak defoliation, late defoliation and non-defoliation. We measured plant nitrogen (N) and phosphorus (P) resorption at species and community levels, and quantified plant N and P fluxes in resorption, litter return and hay output. Plant production in the mowing system was assessed by hay production and quality. Important Findings Peak and late defoliation, but not early defoliation, reduced plant community N and P resorption proficiency (RP); and late defoliation reduced N resorption efficiency (RE) but not P resorption efficiency. Peak and late defoliation, but not early defoliation, reduced plant nutrient resorption flux and litter nutrient return flux. Defoliation timing did not alter root nutrient accumulation as nutrient uptake from soil likely compensated the deficit of nutrient resorption. Peak defoliation had the highest hay production and quality, while early defoliation had the lowest. Our results provide new insights into the nutrient cycling in mowing grassland, and imply that the mowing timing can be used as a tool to mediate the balance between conservation and production of steppes, and the early mowing before plant peak biomass period is recommended for conservation of the steppes while keeping sustainable pastoral production.

Vertical distribution and production of fine roots in an old-growth forest, Japan

Fine roots (≤ 2 mm in diameter) account for up to 50% of total net primary production in forests, representing a major flow of both carbon and nutrients into the soil. We investigated the vertical distribution and production of fine roots in a warm temperate old-growth evergreen broadleaved forest in southwestern Japan. We used a continuous inflow method that considered different rates of diameter-dependent root mortality, decomposition, and thickening. Fine roots were classified into two classes (≤ 1 mm and 1–2 mm diameter). The experiment was conducted over a 1-year period to collect data on the mass of live fine roots and mass of dead fine roots in January, May, November and the following January. Decomposition ratios were assessed for three intervals (January to May, May to November, and November to January). More than 70% of fine roots occurred in the 0–20 cm soil layer, and less than 4% were found in the 50–80 cm soil layer. Decomposition ratios varied seasonally in both root size classes, peaking in summer and reaching a minimum in winter. The same pattern was found for production, mortality, and decomposition. The peak rate of production was 1.62 g·m–2·day–1 in ≤ 1 mm and 0.63 g·m-2·day–1 in 1–2 mm fine roots. The lowest production was 0.62 g·m–2·day–1 in ≤ 1 mm and 0.38 g·m–2·day–1 in 1–2 mm fine roots. Total fine root production over a 1-year period was 6.61 t·ha–1. A mass of 2.70 t·ha–1yr–1 of dead fine roots was decomposed to return nutrients to the soil. It is concluded that a warm temperate old-growth evergreen broadleaved forest in southwestern Japan plays an important role in carbon cycle and nutrient return through a high amount of production and decomposition.

Litterfall deposition and nutrient return in pine-oak forests and scrublands in northeastern Mexico

Litterfall and its decomposition represents the main nutrient input in forest soils whereby organic matter is cycled, thus influencing the circulation of nutrients in ecosystems. Therefore, the aim of this study was to determine litterfall nutrient-input and deposition via fallen leaves. Litterfall was collected at three sites: 1) a pine-oak forest, 2) an ecotone in a transition zone between a pine-oak forest and a piedmont shrubland, and 3) a thorn scrub in the Tamaulipan thorn-scrub vegetation community. At each site, an experimental plot was selected to allocate ten litter canisters to collect litterfall. Total litterfall deposition was highest at the ecotone, followed by the thorn scrub and the pine-oak forest (hereupon, the pine-oak forest will be referred to as “pine forest” for simplicity) (706.0 g m-2 year-1, 495.6 g m-2 year-1, and 483.0 g m-2 year-1, respectively). Leaf litter abundance was greater than that of twigs, reproductive structures, or miscellaneous components (385.3 g m-2 year-1, 84.6 g m-2 year-1, 55.7 g m-2 year-1, and 35.8 g m-2 year-1, respectively). Total deposition of nutrients (mg m-2 year-1)varied as follows: Ca, from 3.7 (pine forest) to 13.5(thorn scrub); K, from 1.0 (pine forest) to 3.8 (ecotone); Mg, from 0.5 (pine forest) to 1.3 (ecotone); N, from 2.7 (pine forest) to 8.3 (ecotone); P, from 0.1 (pine forest) to 0.3 (ecotone); Cu, from 1.0 (pine forest) to 2.9 (ecotone); Fe, from 35.2 (pine forest) to 89.3 (ecotone); Mn, from 27.7 (pine forest) to 71.8 (ecotone), and Zn from 7.3 (thorn scrub) to 7.8 (ecotone). Litterfall and nutrient input was more abundant during the months of winter than at any other time of the year.