Struktur Dan Komposisi Vegetasi Mangrove Di Kawasan Laguna Segara Anakan Cilacap

In coastal areas, mangrove communities have many functions economically, physically, and ecologically. One of the mangrove forest areas that is experiencing rapid decline in area is the Segara Anakan Lagoon, Cilacap. The purpose of this study was to determine the structure and composition of mangrove vegetation. Vegetation data was collected by purposive sampling method and each station was made 9 sampling plots. The results found that there are 12 species consisting of 4 major mangrove families, 1 minor mangrove family and 2 associated mangrove families. In general, the mangrove tree vegetation in the eastern part of Segara Anakan is dominated by Aegiceras corniculatum with an INP ranging from 38.99-67.23%, the middle part is dominated by Nypa fruticans with an INP ranging from 47.80-70.18% and the western part is dominated by Sonneratia alba with an INP of 56.32%. Environmental quality measures include water temperature, salinity, dissolved oxygen, soil pH, water pH, TSS, total soil N, organic C, soil phosphate still support mangrove life.

Pengaruh Kompos Ela Sagu dengan Mikroorganisme Antagonis Terhadap Kemasaman, P Tersedia dan N-Total Tanah pada Ultisols

Agricultural waste, such as sago ‘ela’ or sago extraction waste, can be used as an organic fertilizer to improve the physical, chemical and biological properties of the soil. In addition to organic fertilizer from sago ‘ela’, microorganisms can also be used to increase soil fertility. The purpose of this study was to examine the effect of sago ‘ela’ compost and antagonistic microorganisms in the process of changing acidity (pH and Al-exc), availability of P, and total N in Ultisols soil. The research took place at the Laboratory of Soil, Water, and Plant Analysis, Faculty of Agriculture, Pattimura University, Ambon, in June - September 2016. The experiment was carried out with a completely randomized design (CRD) with a factorial arrangement of 4 x 3, with 3 replications. The treatments of providing sago ‘ela’ compost consisted of: no compost (K0), 15 g/kg of soil (K1), 22, 5 g/kg of soil (K2), 30 g/kg of soil (K3). Inoculum provision of antagonistic microorganisms consisted of: without inoculum (A0), Trichoderma sp inoculum 20 mL (A1), and Azotobacter sp inoculum 20 mL (A2). The experiment used 3 replications. The results showed that soil pH was increased by compost and antagonistic microorganisms. However, the effect of compost does not depend on the presence or absence of antagonistic microorganisms and vice versa. Al-exc concentrations were reduced by compost and microorganisms, but the effect of microorganisms only occurred in the soil without compost and in the treatment of 15 g/kg of soil (K1). Above these compost doses, the effect of microorganisms was not significant. The concentrations of available P and total soil N were increased by compost and microorganisms, and the effect of compost was greater if accompanied by the application of Azotobacter sp. Keywords: acid soil, antagonistic microorganisms, compost, sago‘ela’ ABSTRAK Limbah pertanian, seperti ela sagu atau limbah ekstraksi sagu, dapat digunakan sebagai bahan pupuk organik untuk memperbaiki sifat fisik, kimia dan biologi tanah. Selain pupuk organik dari ela sagu, mikroorganisme juga dapat digunakan untuk meningkatkan kesuburan tanah. Tujuan penelitian ini adalah untuk mengkaji pengaruh pemberian kompos ela sagu dan mikroorganisme antagonis dalam proses perubahan kemasaman (pH dan Al-dd), ketersediaan P, dan N total pada tanah Ultisols. Penelitian berlangsung di Laboratorium Analisis Tanah, Air, dan Tanaman Fakultas Pertanian, Universitas Pattimura Ambon, pada bulan Juni - September 2016. Percobaan dilakukan dengan Rancangan Acak Lengkap dengan pola faktorial 4 × 3, dengan tiga ulangan. Perlakuan pemberian kompos ela sagu terdiri atas: tanpa kompos (K0), 15 g/kg tanah (K1), 22,5 g/kg tanah (K2), 30 g/kg tanah (K3). Pemberian inokulum mikroorganisme antagonis terdiri atas: tanpa inokulum (A0), inokulum Trichoderma sp 20 mL (A1), dan inokulum Azotobacter sp 20 mL (A2), Percobaan menggunakan 3 ulangan. Hasil penelitian menunjukkan bahwa pH tanah ditingkatkan oleh kompos dan mikroorganisme antagonis. Tetapi, pengaruh kompos tidak tergantung pada ada atau tidak adanya mikroorganisme antagonis dan sebaliknya. Kosentrasi Al-dd diturunkan oleh kompos dan mikroorganisme, tetapi pengaruh mikroorganisme hanya terjadi pada tanah yang tidak diberi kompos dan pada perlakuan 15 g/kg tanah (K1). Di atas dosis kompos tersebut pengaruh mikroorganisme tidak nyata. Konsentrasi P tersedia dan N total tanah ditingkatkan oleh kompos dan mikroorganisme, dan pengaruh kompos lebih besar jika disertai pemberian Azotobacter sp. Kata kunci: ‘ela’ sagu, kompos, mikroorganisme antagonis, tanah masam

Enhancing Soil Fertility through Intercropping, Inoculation and Fertilizer

The present study was conducted to investigate the effects of intercropping grass (Panicummaximum) and legumes (Vicia sativa and cowpeas) alone or coupled with inoculation or fertilizer on soilfertility. The study comprised of two field experiments conducted under rain fed conditions for two years(June, 2005 to September, 2007) at National Agriculture Research Centre, Islamabad, Pakistan. In oneexperiment intercropping (33, 50 and 67%) of grass and legumes alone as well as coupled with seedinoculation were studied while, same set of treatments was combined with fertilizer application at the ratesof 25, 75 and 50 kg/ha (N, P2O5 and K2O) in the second experiment. Total soil N increased by 0.008% dueto symbiotic fixation in addition to plant uptake under best treatment when compared with grass alonewhile, soil organic matter increased by 0.19%. After crop harvest soil N content was determined to behigher in all the treatments of the experiment compared with growing grass alone. Legumes caused rhizobialN fixation that caused an increase in soil N. Similarly, intercropping and inoculation increased this soilcharacteristic that was found to be non-significant in the first crop but later on became significant, especiallywhen intercropping of grass with legumes after seed inoculation was investigated or fertilizer wassupplemented to the crops. Thus, not only grass used the symbiotically fixed N by companion legumesbut also enhanced the soil N content. The effect of fertilizer was not measurable statistically in case of soilorganic matter. This parameter, in general, was not affected significantly when assessed after first cropharvest. Nevertheless, legumes alone or intercropped within grass increased this important soil constituent.Inoculation proved further beneficial in this regard but combination of intercropping (especially 67%)either with seed inoculation or application of fertilizer was found as the best technique for increasing soilorganic matter.

Nitrogen Management in Organic Processing Tomato Production: Nitrogen Sufficiency Prediction Through Early-season Soil and Plant Monitoring

Organic processing tomato (Solanum lycopersicum L.) production is a significant industry in California, yet little nitrogen (N) fertility research is available to guide N management. A total of 37 certified organic processing tomato fields in the Sacramento Valley of California were monitored during the 2012 and 2013 production seasons, with two objectives: 1) to document current N management practices and 2) to investigate the utility of early-season soil and plant N monitoring techniques in predicting seasonal crop N sufficiency. Between ≈3 and 11 weeks after transplanting (WAT) soil mineral N (SMN), leaf N and petiole NO3-N were determined every other week. In 22 fields, whole plant N concentration at ≈11 WAT was determined as a measure of crop N sufficiency. Growers were surveyed regarding N management practices used and fruit yields achieved. Net N mineralization (Nmin) was measured for 20 fields soils by aerobic laboratory incubation. Carbon mineralization (Cmin) in 24 hours following rewetting of air-dried soil and water extractable organic nitrogen (WEON) and carbon (WEOC) were also determined and evaluated as predictors of Nmin. Nitrogen management was primarily based on the application of manure or manure compost in the fall. Organic fertilizers were applied mainly in spring (pre- and post-transplanting). SMN in the top 60 cm at 3 WAT ranged from 6 to 32 mg·kg−1. About 30% of fields were N deficient by 11 WAT. Sensitivity analysis showed that SMN (whether measured from 0 to 30 or 0 to 60 cm) and leaf N at 5 WAT correctly predicted late-season plant N status in >60% of the fields. Nmin in 28 days ranged from 8 to 31 mg·kg−1, representing an average of 2% of total soil N. Correlation between Nmin and Cmin was weak (r = 0.44, P = 0.051) while stronger correlations were observed between Nmin and WEOC, WEON and total soil N (r = 0.63, 0.61 and 0.51, respectively, all P < 0.03). A multiple linear regression model that used 3 WAT SMN (0–30 cm) and WEON as independent variables improved Nmin prediction (adj. R2 = 0.67). Significant fruit yield increase with sidedress N application of feather meal at 5–6 WAT was observed in 2 of 4 field trials, demonstrating the ability to remedy a soil N limitation identified by early-season N monitoring.

The Spatial Factor, Rather than Elevated CO2, Controls the Soil Bacterial Community in a Temperate Forest Ecosystem

ABSTRACT The global atmospheric carbon dioxide (CO2) concentration is expected to increase continuously over the next century. However, little is known about the responses of soil bacterial communities to elevated CO2 in terrestrial ecosystems. This study aimed to partition the relative influences of CO2, nitrogen (N), and the spatial factor (different sampling plots) on soil bacterial communities at the free-air CO2 enrichment research site in Duke Forest, North Carolina, by two independent techniques: an entirely sequencing-based approach and denaturing gradient gel electrophoresis. Multivariate regression tree analysis demonstrated that the spatial factor could explain more than 70% of the variation in soil bacterial diversity and 20% of the variation in community structure, while CO2 or N treatment explains less than 3% of the variation. For the effects of soil environmental heterogeneity, the diversity estimates were distinguished mainly by the total soil N and C/N ratio. Bacterial diversity estimates were positively correlated with total soil N and negatively correlated with C/N ratio. There was no correlation between the overall bacterial community structures and the soil properties investigated. This study contributes to the information about the effects of elevated CO2 and soil fertility on soil bacterial communities and the environmental factors shaping the distribution patterns of bacterial community diversity and structure in temperate forest soils.

Soil and Douglas-fir (Pseudotsuga menziesii) foliar nitrogen responses to variable logging-debris retention and competing vegetation control in the Pacific Northwest

Experimental treatments of logging-debris retention (0%, 40%, or 80% surface coverage) and competing vegetation control (initial or annual applications) were installed at two sites in the Pacific Northwest following clearcutting Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. menziesii) stands to assess short-term effects on tree N acquisition, soil N supply, and total soil N. Vegetation control treatments began in the first year after harvest, and logging-debris manipulations were installed 2 years after harvest. Annual vegetation control increased foliar N concentration and content in most years at both sites, which was associated with higher available soil N and increased soil water content. Logging-debris retention treatments had no detectable effect on any of the foliar variables or soil available N at either site. There were no treatment effects on total soil N at the site with relatively high soil N, but total soil N increased with logging-debris retention when annual vegetation control was applied at the site with a low initial soil N pool. Competing vegetation control is an effective means to increase tree N acquisition in the initial years after planting while maintaining soil N pools critical to soil quality. The effect of logging-debris retention on tree N acquisition appears to be limited during early years of stand development, but increased soil N with heavy debris retention at certain sites may be beneficial to tree growth in later years.

Residual effects of phosphorus and soyabean crop on maize in the Guinea savanna of West Africa

Two seasons of cropping were carried out at three sites in the Guinea savanna to evaluate the residual effects of soyabean on maize. The experiment was laid out as a splitplot design in a randomized complete block with three replications. In the first season, four soyabean varieties with a fallow treatment (control) received phosphorus (P) applied as triple superphosphate (20% P) at the rates of 30 and 60 kg P ha −1 . Maize was grown in these plots in the second season without fertilizer application. At all sites, regardless of the previous crop, total soil N remained low (<1.5 g kg −1 ). Available P was affected by the P rate in the previous year at all sites. From initial values ranging from 5.2–16.2 mg kg −1 in the first season, available P significantly (p<0.05) increased in the second season to 9.8–42.8 mg kg −1 when 30 or 60 kg P ha −1 was applied, compared to 7.7–18.6 mg kg –1 at no P application. Relative to no P application in the previous year, the application of 60 kg P ha −1 significantly increased total dry matter at 6 weeks after planting by 19%, total harvest dry matter by 28%, and grain yield by 37%.

Effects of nitrogen application rate on soil and plant characteristics in pastures of perennial grass mixtures in the alpine region of the Qinghai-Tibetan Plateau, China

To illustrate the effect of nitrogen (N) application on soil physical and chemical characteristics, herbage yield and quality, and nitrogen and water use efficiency in the alpine region of Qinghai-Tibetan Plateau, a 3-year experiment was conducted on 3 mixtures of 4 perennial grasses commonly cultivated on the Plateau, Bromus inermis (BI) + Elymus nutans (EN), BI + E. sibricus (ES) + Agropyron cristatum (AC), and BI + ES + EN + AC by applying 4 levels of N fertiliser, 0, 115, 230, and 345 kg/ha from 1998 to 2000 in a randomised design. At harvesting time, soil pH and soil dry bulk density at 0–30 cm depth did not vary with N application rate. Soil organic carbon at 0–30 cm was not significantly variable under different N rates. Total soil N at 0–30 cm increased with N application rate and application year. After 3 years’ consecutive N treatment, total soil N reached 13 g/kg at an N application rate of 345 kg/ha. Soluble soil N at 0–30 cm increased with application rate but decreased with application year. At 345 kg N/ha application rate, soluble soil N was >100 mg/kg in 1998, but decreased to around 80 mg/kg in 2000. Herbage DM yields increased linearly with the N application rate. Compared with no fertiliser, 1.5 times more DM yield in 1998 and nearly double the DM yield in 1999 and 2000 were harvested for all grass mixtures at 345 kg N/ha. N concentrations in the herbages were significantly improved by N application. Each N fertiliser rate increased N contents in grass herbages by ≈3 g organic matter/kg. Apparent nitrogen recovery (ANR) decreased with N application rate in the establishment year of 1998, but increased with N application rate in 1999 and 2000. N use efficiency (NUE) decreased with N application throughout the experiment. Precipitation use efficiency (PUE) was significantly improved by N application for each grass mixture. Positive residual N-fertiliser effects were observed on herbage DM yield, ANR, NUE, and PUE in this study. BI + ES + AC showed higher DM yields, ANR, NUE, and PUE than the other 2 grass mixtures, and thus was proposed for N-input grassland systems in the alpine region of the Qinghai-Tibetan Plateau.

Variability of δ15N in soil and plants at a New Zealand hill country site: correlations with soil chemistry and nutrient inputs

This study investigated 15N enrichment and nutrient cycling in hill country used for semi-extensive pastoral agriculture, at a site where pre-European seabird breeding occurred. Soil (0–15 cm) and plant samples were taken from 18 ridgeline and sideslope transects. Three stock camps (locations which grazing animals frequent) were identified within the study area, two on the ridgeline and one on the sideslope. Soil 15N enrichment was greatest at stock camps, and lowest where stock input was minimal. Soil natural abundance 15N (δ15N) was therefore an index of stock nutrient inputs. Soil δ15N increased with decreasing C: N ratio, consistent with N loss through volatilisation and/or nitrate leaching from net mineralisation. Plant δ15N from stock camps was lower than its associated soil, implying that 15N enrichment of plant-available N was lower than that of total soil N. However, the correlation between plant δ15N and soil δ15N varied between stock camps, indicating differences in N cycling. Olsen P was higher at stock camps, although again differences were found between stock camps. Total P and N were correlated neither with stock camps nor topography, but were higher than expected from parent material concentrations and literature results, respectively. It is postulated that significant contributions of both elements from former seabird breeding remain in the soil.