NPK Plots Research Articles

Long-term fertilisation impact on temperature sensitivity of aggregate associated soil organic carbon in a sub-tropical inceptisol

Understanding impact of long-term fertilisation on soil aggregation, carbon (C) stabilisation and temperature sensitivity of soil organic C (SOC) mineralisation are necessary to foresee C dynamics. The present study was conducted in an Inceptisol under wheat (Triticum aestivum) based cropping system, with the objective to quantify the effect of 44 years of integrated nutrient management on soil aggregation, enzymatic activity, and temperature sensitivity (Q10) of SOC. Treatments were: unfertilised control (UC), 100% recommended dose of nitrogen (N), N and phosphorus (NP), N, P and potassium (NPK), integrated application of NPK and farmyard manure (FYM) (NPKF) and 150% recommended dose of N, P and K (1.5NPK). The observed data were analysed using analysis of variance for randomized block design and Tukey’s HSD test (P < 0.05) was used for mean separation. In the 0–15 cm soil layer, plots under NPKF had ˜121 and 19% larger macroaggregate-associated C than UC and NPK plots, respectively. Irrespective of soil depth and temperature, higher cumulative C mineralisation was observed for NPKF (by ˜67-91%) and NPK (by ˜42-56%) treated plots than UC. Activation energies for SOC decomposition in 0–15 cm bulk soil were ˜205, and 258% higher in NPKF, and 1.5NPK, respectively, than UC plots. Mean Q10 of macroaggregate-C was higher than microaggregate-C. Aggregate-C of sub-surface soil was more temperature sensitive than surface soil, possibly due to higher recalcitrant/total SOC in the subsurface than surface layer. Thus, it reveals the need of better C management practices to augment the lability of C in subsurface soil layers. Plots under NPKF had higher β–glucosidase and fluorescein diacetate activities in bulk soils and aggregates over NPK in the both layers. NPKF application is recommended for improved soil aggregation, SOC protection within macroaggregates, enzyme activities in bulk soils and aggregates and capable for less proportional SOC decomposition than NPK or UC plots at higher temperature. Thus, soil management involving organic manure application and mineral fertilisers would enhance the activation energy of SOC and act as a barrier for SOC decomposition by facilitating soil aggregation and enhance SOC sequestration.

Stoichiometric analyses of soil nutrients and enzymes in a Cambisol soil treated with inorganic fertilizers or manures for 26 years

The biogeochemical interactions between soil nutrients and microbial enzymes in agroecosystems remain poorly understood. The objective of this study was to determine effects of long-term (26 years) application of chemical fertilizers (NPK) or adding manure (M) on the elemental and the enzymatic functional stoichiometric characters in a brown soil. The concentrations of soil elements, i.e. carbon (C), nitrogen (N), phosphorus (P) and sulfur (S) and the activities of soil hydrolases including α (β)‑galactosidase (α-GAL and β-GAL), α (β)‑glucosidase(α-GLU and β-GLU), urease, protease (PR), phosphomonoesterase (PM), Phosphodiesterase (PD) and arylsulfatase (AS) were investigated.Results showed that the NPK additions alone led to a decrease in soil pH and increased the acidification of the soils, while M additions could buffer the acidification. With doubling application rate of M, the concentrations of soil C, N, P and S, and soil enzymes activities increased significantly, but P concentrations increased stronger (doubled) than C and N contents (increased by 30%), leading to shifts in element stoichiometry in response to fertilizer and manure applications. The manure additions led to a relatively constant C:N ratio, a low C:P ratio and a high C:S ratio but lower functional ratios of ln (β-GLU + α-GLU + α-GAL + β-GAL): ln(urease + PR); ln(GLU + GAL): (PM + PD); and ln(GLU + GAL):ln(AS), which implied high availability of P and low availability of S. The comparison of element and enzyme stoichiometry indicated that N and S were limited in the manure plots, and C and P were limited in the NPK and No-NPK fertilizer treatment (WF) plots. The increase in enzyme activities in manure plots was caused primarily by the accumulation of soil nutrients with M treatment and not by a buffering effect on the pH.

Long-term silicate fertilization increases the abundance of Actinobacterial population in paddy soils

Silicon (Si) is widely used in improving crop yield, but effect of its application on soil bacterial community composition is poorly known. Quantitative PCR and high-throughput sequencing targeting the bacterial 16S rRNA gene were employed to characterize the bacterial community composition of long-term fertilized paddy soils treated with nitrogen (N), phosphorus (P), potassium (K), and Si (NPK + Si), with NPK or not fertilized (control). The NPK + Si fertilization significantly increased the urease and dehydrogenase activity. The relative abundance of Actinobacteria was significantly higher in the NPK + Si soil than in other two soils. Linear discriminant analysis (LDA) and effect size (LEfSe) analysis demonstrated that Actinobacteria and its associated taxonomic groups were significantly more abundant in the NPK + Si-treated plots. The bacterial community composition of the NPK + Si soil was significantly different from those of NPK and control soils as shown by the ordination plot. According to distance-based regression analysis, variation in bacterial community composition was related to available SiO2 and P2O5 concentrations. Functional profiles predicted from 16S rRNA abundance data showed that the NPK + Si plots were more enriched by genes coding enzymes related to plant growth promotion compared to NPK and control plots.

Shifts in Nitrobacter- and Nitrospira-like nitrite-oxidizing bacterial communities under long-term fertilization practices

Nitrite-oxidizing bacteria (NOB) are key players in the second step of nitrification, which is an important process in the soil nitrogen (N) cycle. However, the ecology of nitrite oxidizers and their response to disturbances such as long-term fertilization practices are scarcely known in agricultural ecosystems. We used samples from a Red soil subject to a long-term chemical and organic fertilization experiment, including control without fertilizer (CK), swine manure (M), chemical fertilization (NPK), and chemical/manure combined fertilization (MNPK) treatment, to explore how agricultural practices impact the community structure, abundance, and potential activity of nitrite oxidizers (PNO). The abundance of Nitrobacter was significantly increased in the M and MNPK plots, whereas the abundance of Nitrospira was significantly reduced in the M and NPK treatment plots and less inhibited in the MNPK treatment. The PNO showed a similar trend to that for Nitrobacter abundance. The diversity of Nitrobacter increased in the M-treated plots, while that of Nitrospira increased in the M and MNPK plots and decreased in the NPK plots. Non-metric multidimensional scaling (NMDS) revealed that the Nitrobacter- and Nitrospira-like NOB community was shift in these four fertilization treatments. Redundancy analysis showed that pH+SOC (soil organic carbon) and pH+TN (total nitrogen) significantly explained the variation in the composition of Nitrobacter and Nitrospira, respectively. In addition, the Nitrospira/Nitrobacter abundance ratio and community structure of Nitrobacter- and Nitrospira-like NOB are responsible for the changes of soil PNO. Collectively, these data suggest that the nitrite-oxidation process in the red soil is possibly controlled by both Nitrospira and Nitrobacter-like NOB, which were shaped by pH+TN and pH+SOC, respectively.

Inoculum effect of arbuscular mycorrhizal fungi on soybeans grown in long-term bare-fallowed field with low phosphate availability

ABSTRACTInoculation with arbuscular mycorrhizal fungi (AMF) can increase the growth of host plants, especially under condition of low phosphate (P) availability. Although this effect is shown relatively easily in simplified systems such as pot experiments, it is often hard to show in the field because of complicating factors such as competition with indigenous AMF. We conducted an AMF inoculation experiment with three Japanese soybean cultivars (Enrei, Misuzudaizu, and Akishirome) in an allophanic (Umbric Silandic) Andosol field under the long-term selective application of major nutrients (NPK and -P) and bare fallow. In the inoculation plots, introduced AMF were well colonized in soybean roots at flowering stage. In the -P plots, inoculation tended to increase the shoot dry weight of all the three soybean cultivars; this effect remained until harvest. Although a significant difference is not recognized, there was a tendency of residual effect on Enrei in the following year. In the NPK plots, inoculation did not significantly increase the shoot dry weight. We thought that in the -P plots, the long-term selective application of N and K and the long-term maintenance of bare fallow created the soil conditions of low P availability and poor native AMF. Thus, introduced AMF can benefit soybean growth and yield in the soil with low competitor AMF density and low phosphate availability.

Dependence of Thermal and Moisture Sensitivity of Soil Organic Carbon Decomposition on Manure Composition in an Inceptisol Under a 5‐Year‐Old Maize‐Wheat Cropping System

AbstractHydrothermal sensitivity of soil organic carbon decomposition in relation to global climatic changes is of great importance for C cycle in an agro‐ecosystem. To assess the sensitivities of SOC as affected by different organic sources and mineral fertilizer in Inceptisol, soil samples from a 5‐year‐old field experiment were collected from unfertilized control, 100% NPK, vermicompost, compost, and farmyard manure (FM) treated plots and analyzed for total organic C, labile C fractions and C mineralization kinetics by incubating soils at 25 and 35°C temperatures, and 0.33 and 1.0 bar soil moisture for 90 days. Compost and FM‐treated plots had ~23 and 22% higher total organic C than 100% NPK plots, respectively. Plots under vermicompost had similar C management index to FM but ~12% higher than compost. At 25°C temperature and 1.0 bar moisture, CO2 evolutions from vermicompost‐ and FM‐treated plots were ~29 and 11% higher than compost, respectively. Carbon decay rate was invariably higher in control and 100% NPK than organically amended plots. Temperature sensitivity of C was similar at 0.33 bar but different at 1.0 bar among the treatments. Moisture sensitivity of C in organic amended plots was similar at 35°C but different at 25°C, but their moisture sensitivity values were always higher than NPK. It could be concluded that manures with low C/N ratio and high N and P content would reduce C decay rate. Hence, to enhance C sequestration and reduce CO2 emissions in changing climatic situation, organic manure like vermicompost could be recommended.

Site Specific Nutrient Management for Maize on Ultisols Lampung

Site Specific Nutrient Management for Maize on Ultisols Lampung (A M Murni, JM Pasuquin, and C Witt): Lampung is the third major maize producing province in Indonesia after East Java and Central Java. In Lampung maize is cultivated mainly in upland areas with ultisols and only some cultivated on paddy field as a secondary crop in the dry season. The average maize yield in Lampung is still 3.4 Mg ha-1 bellow yield potential of 7-10 Mg ha-1. To increase the productivity of maize through site-specific nutrient management (SSNM), on-farm trials were conducted in five locations in Lampung i.e. four locations in Central Lampung District (Sidowaras, Binjai Ngagung, Watu Agung and Balai Rejo) and one location in South Lampung District (Trimulyo, Tegineneng Sub District) during the 2004/2005, 2005/2006 and 2006/2007 rainy seasons. The experimental setup followed a standard protocol at all sites and included nutrient omission plots (PK, NK, NP) to estimate indigenous nutrient supplies, an NPK plot to measure yield response to fertilizer application, and a farmers’ fertilizer practice (FFP) plot in each farmer’s field. An SSNM treatment plot was included in the second and third seasons. Each of the above treatments was paralleled by a plot with improved crop management practice (ICM), i.e. higher planting density, addition of lime, and addition of magnesium. Results showed that yield response to fertilizer N, P and K application in these sites were: N = 2.3-4.1 Mg ha-1; P = 0.6-2.0 Mg ha-1; K = 0.3-2.4 Mg ha-1. Attainable yield in the three seasons on average ranged from 7.6 Mg ha-1 to 10.6 Mg ha-1. Yield in the SSNM treatment (with or without ICM) was significantly higher than the FFP indicating great opportunities for farmers to increase productivity and profitability with improved nutrient and crop management.

Yield and nutrient uptake by maize as influenced by phosphorus and zinc application

Bulk soil samples from a long term (45 years) experiment were collected with three treatments (100% N, 50% NPK and 100% NPK) to represent different soil fertility levels for green house study using maize as test crop. To each soil, combinations of 4 levels of P (0, 30, 60 and 120 mg P kg−1) and Zn (0, 6.25, 12.5, 25 mg Zn kg−1) were applied in pots containing 4 kg soil. The effects of different levels of P and Zn were examined on dry matter yield, P and Zn concentrations and their uptake at 45 days after sowing. Soil collected from 100% N plots had the highest dry matter yield and P concentration but the lowest Zn concentration in maize plants. Soil from 100% NPK plots had the highest Zn concentration but lowest dry matter yield. Phosphorus application increased dry matter yield, whereas Zn had minimal effect on dry matter yield. Significant effect of P on Zn concentration was observed, whereas Zn had no effect on P concentration in maize plants.

Subsoil phosphorus is affected by fertilization regime in long‐term agricultural experimental trials

SummaryArable subsoils store large amounts of phosphorus (P); however, it is unclear to what extent, and under which conditions, subsoil resources might supplement crop P acquisition. Here, we hypothesized that (i) insufficient supply of P in topsoil promotes P acquisition from subsoil and (ii) subsoil P cycling is regulated by nitrogen (N) supply. We sampled two German long‐term fertilizer trials in Thyrow (sandy soil) and Gießen (loamy‐clayey soil) to 100‐cm depth. Treatments received either NPK, NK or PK fertilizer for &gt; 60 years. We assessed soil inorganic (Pi) and organic (Po) P pools following Hedley sequential extraction, and the oxygen isotopic composition of HCl‐extractable phosphate (δ18OHCl‐P), which differentiates P from primary and secondary (previously biologically cycled) minerals. We found that in the Hedley sequential extraction subsoil resin‐P stocks (30–100 cm) in NK plots were 60% (Thyrow) and 8% (Gießen) less than those in NPK plots. Subsoil HCl Pi stocks in NK exceeded those of NPK plots by 70% in Thyrow, but not in Gießen. The NK treatments showed significantly smaller subsoil δ18OHCl‐P values than NPK treatments, indicating a predominance of primary (not biologically cycled) minerals and refuting our hypothesis that P deficiency promotes P acquisition from primary minerals. Under N‐limiting conditions, subsoil resin‐P stocks exceeded those under NPK fertilizer by 117% (Thyrow) and 22% (Gießen), supporting our second hypothesis. We conclude that an efficient use of subsoil P resources is achieved only when nutrient supply in arable topsoils is sufficient.Highlights Long‐term N and P fertilization promotes use of P from subsoil (&gt; 30-cm depth) Subsoil stocks of resin P were less in NK than NPK fertilized plots Elevated δ18OHCl‐P in the subsoil of NPK plots indicates effects by enzymatic activity Small δ18OHCl‐P values in the subsoil of NK plots indicate a predominance of primary minerals

Long-term fertilization effects on soil organic carbon sequestration in an Inceptisol

Limited information is available on long-term fertilization impacts on soil organic carbon (SOC) sequestration in deep soils and C pools within bulk soils and aggregates. Hence, the major objectives of this study were to evaluate long-term (44 years) fertilization impacts on: (i) soil aggregation, labile and recalcitrant C pools within bulk soils and aggregates and (ii) deep soil C accumulation versus sequestration. Treatments were: no mineral fertilizer or manure (control), 100% recommended dose of nitrogen (N), N and phosphorus (NP), N, P and potassium (NPK), 150% recommended NPK (150% NPK), and NPK + farmyard manure (FYM) (NPK + FYM). Labile C, recalcitrant C, total SOC and glomalin in bulk soils and their aggregates were determined in the 0–15 and 15–30 cm soil layers. In addition, total SOC, labile and recalcitrant C contents were measured in the 30–60 and 60–90 cm soil layers. Results revealed that C accumulation and sequestration in NPK + FYM over control plots were 0.74 and 0.22 Mg C ha−1 yr−1, respectively, in 0–90 cm soil layer with >50% of the accumulated C in deep soil layers (30–90 cm). In 0–15 cm layer, despite NPK + FYM and NPK plots had similar amounts of soil macroaggregates, microaggregates were 27% higher with NPK + FYM than NPK, causing higher aggregate stability. Plots with NPK and NPK + FYM had more labile: recalcitrant C ratios in bulk soils than control, NP and N plots. The NPK + FYM plots also had highest recalcitrant C pools within macro- and microaggregates. Glomalin was generally positively correlated with all labile C pools in both soil layers. Additionally, mean weight diameter (MWD) was positively correlated with aggregate-associated C and glomalin within bulk soils. Overall, NPK + FYM management practice not only had higher C accumulation and sequestration in surface and deep soils, but also had better aggregation and ∼26% greater carbon management index than NPK in soil surface and hence should be adopted.

DRIP FERTIGATION REGIME FOR POTATO ON SANDY SOIL

To establish the optimum fertilizer rate and propose an appropriate drip fertigation regime for potato (Solanum tuberosum L.) on sandy soil, a two-year field experiment comparing different fertigation levels on potato yield, irrigation water productivity (IWP) and partial fertilizer productivity (PFP) was carried out during 2012–2013. The treatments included five fertigation levels: 10%, 30%, 50%, 70% and 90% of the recommended fertilizer dose of 420:105:495 of N:P:K in kg ha–1 year–1 in 2012; and 10%, 35%, 60%, 85% and 110% of the recommended dose of 390:150:465 of N:P:K in kg ha–1 year–1 in 2013. The recommended fertilizer dose was estimated based on the method of nutrient balance for a target yield of 45.0 Mg ha–1. The soil matric potential at 20 cm depth beneath the emitters was controlled above –25 kPa for drip fertigation. Results showed the highest tuber yield was 38.0 Mg ha–1 for 90%NPK in 2012 and 45.8 Mg ha–1 for 60%NPK in 2013, which was significantly higher than that for 10%NPK. The highest IWP was for 70%NPK in 2012 and 60%NPK in 2013. The highest PFP values were 255.5 kg kg−1 in 2012 and 316.4 kg kg−1 in 2013, recorded in the 10%NPK plots and were significantly higher than for other fertigation treatments. High yield levels of potatoes and both high IWP and PFP could be reached by drip fertigation with 72% of the recommended fertilization dose. Compared with the recommended fertilizer dose, the yield and IWP of 72% NPK increased by 5.9% and 4.7%, respectively. It was possible to make average savings in one season alone of 136, 36 and 152 kg ha–1 N, P2O5 and K2O, respectively. In conclusion, drip fertigation with 72% NPK should be considered optimum for potato production on sandy soils. Each fertilizer amount based on irrigation interval was applied with irrigation quota at 5–6 mm when soil matric potential at soil depths of 20 cm immediately under drip emitters reached –25 kPa. Furthermore, drip fertigation was triggered when 10 consecutive days were without fertigation or rainfall in 24 h exceeded 10 mm.

Low temperature carbonization of chicken manure to char and its effect on growth of Oryza sativa L. Koshihikari and Brassica rapa komatsuna

Considering the demand for transforming poultry waste into eco-friendly manure, we carbonized chicken manure at 402, 449 and 528 °C and determined the physicochemical properties. We evaluated the effectiveness of the ensuing carbonized chicken manure (CCM) as a fertilizer using Brassica rapa, var. komatsuna and Oryza sativa L., var. japonica, cv. Koshihikari, in the upland and the paddy field soil, respectively. Herein, we carried out duplicate treatment of CCM (carbonized at 528 °C) either alone or in combination with nitrogen and measured the growth from three or more plants. The plots with the recommended chemical fertilizers containing nitrogen (N), phosphorus (P) and potassium (K) and with no fertilizers were used as controls for growth measurement. The vessel tests indicated that when applied alone, the CCM plot could not support the normal growth of both the plants. However, the CCM plot restored the plant growth with simultaneous application of nitrogen, and the growth in the CCM + N plot was comparable to that observed in the NPK plot. By estimating the growth in the NPK plots as 100%, the growth percentages of fresh weights of komatsuna were 12% in the CCM plot, 79% in the N plot and 99% in the CCM + N plot. Likewise, the plant heights of Koshihikari were 43% in the CCM plot, 77% in the N plot and 99% in the CCM + N plot. Our data suggest CCM supplementation to N fertilizers as a potential replacement of inorganic fertilizers like P and K for effective environmental management.

English

The experiment was conducted at Teaching and Research Farm of University of Port Harcourt between May and August, 2016 to determine the influence of different soil management practices on soil organisms and maize yield (Zea mays L.) in South Eastern Nigeria. The experiment consisted of six treatments, namely:&nbsp; control (no application), cover crop (pumpkin cover), 10 t/ha dry guinea grass mulch (dead mulch), 10 t/ha poultry manure, 250 kg/ha N:P:K 15:15:15 and 10 t/ha dry guinea grass as bush burning material. These treatments were laid out in a Randomized Complete Block Design with four replicates. Results showed that the initial bacterial count was 2.0 &times; 106 CFU/g, fungal count (1.7 &times; 105 cfu/g), and earthworm casts (0). The soil was sandy loam and the pH was very strongly acid (4.80). At 11 weeks after application (WAA), NPK treated plots had the highest bacterial count (4.6 &times; 106 CFU/g), while cover crop and dead mulch plots had the highest fungal count (1.9 &times; 105 cfu/g). At the point of harvest, the highest earth worm casts (19.00) were in cover crop. The most predominant bacteria isolates across the various soil management practices were Bacillus and Pseudomonas species, while that of fungal were Aspergillus niger and Candida species. Maize yield differed significantly (p&lt;0.05) among various soil management practices. In spite of the variation in the population of soil organisms, NPK plots produced the highest yield (170 kg/ha) and is therefore recommended. &nbsp; Key words: Influence, maize yield, soil management practices, soil organisms, Southeastern Nigeria.

Temperature sensitivity of soil organic carbon decomposition as affected by long-term fertilization under a soybean based cropping system in a sub-tropical Alfisol

Understanding temperature sensitivity of soil organic carbon (SOC) decomposition from bulk soils and aggregates of long-term fertilized plots is imperative to forecast soil C dynamics. We evaluated the impacts of 43 years of fertilization under a soybean (Glycine max) based cropping system on temperature sensitivity of SOC decomposition (Q10) in an Alfisol. Treatments were: no mineral fertilizer or manure (control), 100% recommended dose of nitrogen (N), N and phosphorus (NP), N, P and potassium (NPK), NPK+lime at 0.4Mgha−1 (NPK+L), 150% recommended NPK (150% NPK), and NPK+farmyard manure (FYM) at 10Mgha−1 (NPK+FYM). Bulk soils as well as macro- and micro-aggregates were incubated for 24days at 25°C and 35°C. Cumulative SOC mineralization (Ct) in the 0–15cm soil layer of bulk soils with NPK+FYM and NPK treated plots were similar but significantly higher than unfertilized control plots. However, both Ct and Q10 values in the NPK+FYM plots were higher than NPK in the 15–30cm soil layer. In the 0–15cm soil layer, NPK+FYM plots had ∼10 and 26% greater Q10 values of macro- and microaggregates than NPK. Activation energies required for bulk soils C mineralization was ∼2 and 3 times higher in NPK+FYM and NPK+L plots, respectively, compared with unfertilized control plots in that layer. Lime along with NPK application increased the activation energy of SOC decomposition. Thus, long-term NPK+FYM and NPK+L applications have great potential for less proportional SOC decomposition than NPK or unfertilized control plots under a temperature rise in these acid soils. However, NPK+FYM management practice is recommended as it has highest SOC accumulation and can have less SOC losses under a temperature rise.

Compost effects on leaf area index and seed production enhancement in an important arid land leguminous tree Acacia tortilis subsp. Raddiana

This study aimed to investigate the effects of compost addition on leaf area index (LAI), diameter growth and enhancement of seed production and quality in Acacia tortilis established under supplementary drip irrigation. Three composted fertilizer doses (2.5 kg, 5 kg and 7.5 kg/ tree) were compared to NPK (18-18-5 at a rate of 250 gram per tree) and control unfertilized plots. Effects of compost application on leaf area index (LAI), diameter growth, relative monthly diameter increment (RMDI) were monitored during two consecutive years (2014 and 2015). Then the impacts on pods and seeds production, seed weight, seed number per kg, seed quality (NPK and protein), germination per cent and mean germination time (MGT) were determined. Addition of fertilizers produced high effects on LAI. In 2014 NPK resulted in highest LAI values in most measurements, alternatively the status was changed in 2015 where, higher doses of compost produced higher LAI values. LAI results exhibited temporal variability that was associated with the seasonal variation of the year. The results demonstrate higher RMDI and diameter growth under NPK and compost at rate of 7.5 kg/tree treatments. Pods production was higher in plots treated with higher doses of compost. However, seed/husk ratio was higher in NPK plots. There is observed association between fruit and seed production with LAI. NPK and protein contents in seeds, were also, influenced by the presence of organic fertilizers. Cumulative germination and MGT were correlated with seed weight and were higher in plots treated with compost. The results highlight the importance of organic fertilizers under dry land conditions that produced higher LAI and growth which enhanced seed production and quality.

Soil physical properties and grain yields of lowland rice in response to sawah preparation intensities and soil amendment types

Sawah, an Indo-Malaysian word for rice paddy, is used in West Africa to refer to a lowland rice field that is bunded, puddled and levelled for ease of water control and management. There are insufficient data on lowland soil and rice responses to sawah preparation intensity, defined by relative completeness of these three land preparation activities (bunding + puddling + levelling). This study assessed soil physical properties and rice grain yield under sawah preparation intensities [complete (bunded, puddled, levelled), quasi-complete (bunded, slightly puddled, levelled) and incomplete (bunded, non-puddled/levelled) sawah, and control] and soil amendments [NPK, poultry droppings (PD), rice husk (RH), its ash (RHA) and control] in southeastern Nigeria for 3 years. At rice maturity, soil bulk density increased with decreasing intensity of sawah preparation and was lower with than without amendments, being lowest in RH-amended plots. Aggregate sizes were adversely affected in the three sawah plots and by soil amendments, mainly NPK. Mean-weight diameter of aggregates was always highest in complete sawah, while showing lowest and highest values in NPK and PD plots, respectively. Sawah bunding/puddling and amendments positively affected soil water content. Saturated hydraulic conductivity was always highest in complete sawah plus PD and lowest in the control. Rice grain yield did not always increase with sawah preparation intensity but all sawah plots out-yielded the control after the first year. All amended plots always out-yielded the control, with higher values due to PD/RH compared with RHA/NPK in the third year. Soil physical control of rice grain yield revealed strengths (R2, 0.847–0.420) in decreasing order of conductivity, bulk density/water content, <0.25-mm aggregates and mean-weight diameter. Only soil bulk density related inversely to grain yield up till a critical value of 1.05 g cm−3. Complete sawah or, where improved soil structure after rice is not desired, quasi-complete/incomplete sawah can be combined with organic amendments (PD/RH) to grow lowland rice.

Mineral density of onion bulbs as affected by fertilizers based on elemental sulfur

The yield increase of vegetables, including common onion (Alium cepa L.), is of great interest to growers. However, higher yield often leads to what is known as genetic dilution of mineral density. A technology of onion fertilization based on elemental sulfur (S0) fertilizers seems to be a simple agronomic measure preventing a decrease in the nutrient concentration in onion bulbs. To verify this hypothesis, field studies were conducted in the 2009 and 2010 seasons. A two-factorial trial consisted of five sulfur fertilizers: Sw (crude form of S0), Sm (micronized S0), SmCu (Sm enriched with copper 0.25%), SmZn (Sm enriched with zinc 0.5%), and AS (ammonium sulfate); and, as the second factor, of two doses of S: 30 and 60 kg ha-1. The NPK plot, included as an independent experimental variant, was used as the control. Yield of onion increased by 13% in response to 30 kg S ha-1, and by 44% when fertilized with 60 kg S ha-1. The yield of bulbs was significantly affected by increasing magnesium and negatively by sodium concentration. The increase in both bulb yields and dry matter content resulted in a simultaneous decrease in nutrient density, except sulfur. The strongest dilution effect was observed for sodium (-33%), iron (-19%), magnesium (-17%) and phosphorus (-16%). Such a negative development can be prevented by applying sulfur fertilizers in an appropriate form. The concentrations of N, P, K, N, and Cu responded most demonstrably to the added ammonium sulfate. The concentrations of S, Zn, Cu, Mn, and Fe were affected by the micronized form of S0 enriched with zinc. The magnesium concentration was the highest in plants fertilized with the crude form of S0.

Residual value of inorganic fertilizer and farmyard manure for crop yields and soil fertility after long-term use on a loam soil in Norway

Mineral NPK fertilizer and manure have been compared since 1922 in a ley–arable rotation. During 1982–2003, cattle manure at 20–60 Mg ha−1 year−1 yielded 10–20 % less than mineral fertilizer at 100 kg N:25 kg P:120 kg K ha−1 year−1. The higher manure rates gave large nutrient surpluses. Both manure and mineral fertilizer had increased soil organic carbon (SOC), by 11.3 and 3.4 Mg ha−1 in 1996. In order to study possible residual effects, no manure was applied in 2004–2007 and mineral fertilizer was withheld from some NPK plots. Effects on yield and nutrient uptake were evaluated in relation to plots with no nutrient supply since 1922 and plots still receiving 100 kg N, 25 kg P and 120 kg K ha−1 annually. No residual response of mineral fertilizer was found, but previous manure use gave large effects. The latter yields remained around 85 % of those obtained with mineral fertilizer. Previous use of both mineral fertilizer and manure still increased available soil nutrients and pH in 2007. Differences between treatments in SOC had by then declined slightly, to 9.7 and 2.8 Mg ha−1 for manure and mineral fertilizer respectively, relative to the unfertilized control. Manure and fertilizer applications were resumed in 2008, except at the highest previous manure rate, where mean residual responses up to 2014, relative to the unfertilized control, amounted to 55 % higher yield and increases in nutrient uptake of 47 kg N, 8 kg P and 53 kg K ha−1.

Site-Specific Nutrient Management for Rainfed Maize in Western Mid-Hills of Nepal

On-farm experiment was conducted in eight farmers’ field, of Khasyoli village development committee (952 to 1415 masl), Nepal, from April to September, 2011 to address the major constraint (nutrient management) to maize production through site-specific nutrient management (SSNM) as this approach is popular among scientists. The experiment comprised three nutrient omission plots (0N, 0P, and 0K), an ample NPK plot, and a farmers’ fertilization practice (FFP) plot, arranged in randomized complete block design. Farmers planted open pollinated variety (Manakamana-3) and managed in their way. Field-specific NPK application rates were calculated by considering nutrient demand, indigenous NPK supply and recovery efficiency of fertilizers. Grain yield in FFP (2.32 Mg/ha) and 0N (1.79 Mg/ha) plots differed significantly from each other and rest of the treatments, but was statistically similar among 0P (3.18 Mg/ha), 0K (3.40 Mg/ha) and ample NPK (3.38 Mg/ha) plots. Post-harvest grain and stover analysis revealed that indigenous NPK supply (20-71 kg N, 19-68 kg P2O5 and 51-164 kg K2O/ha) of soil vary among the farmers’ field. Moreover, soil was poor in indigenous N supply (42 kg/ha), but rich in indigenous P2O5 (35 kg/ha) and K2O (90 kg/ha) supply, on an average. As per the principles of SSNM, the initial fertilizer recommendation made can vary from 40-222 kg N, 0- 93 kg P2O5, and 0-50 kg K2O/ha. On an average, farmers may apply no or lower dose of P2O5 (18 kg/ha) and K2O (3 kg/ha) but need to significantly increase dose of N (143 kg/ha) fertilizer for enhancing soil and maize productivity.Int J Appl Sci Biotechnol, Vol 3(2): 227-231 DOI: http://dx.doi.org/10.3126/ijasbt.v3i2.12538

Changes of Chemical Characteristics of Soil Solution In Paddy Field from Fifty-Eight Years Fertilization Experiments

The objectives of this study were to monitor the changes in soil solution nutrients and to evaluate their effect on rice uptake and yield. The changes of chemical characteristics of paddy soil solution were examined from the 58th fertilization experiment in which the continuous rice cropping experiment started in 1954 at the National Academy of Agricultural Science. The treatments were no fertilization (No fert.), inorganic fertilization(NPK), inorganic fertilizer plus rice straw compost (NPKC) and inorganic fertilizer plus silicate and limefertilizer as a soil amendment (NPKCLS). The fertilizers were added at rates of standard fertilizer application rate in which nitrogen (N), phosphate (P₂O 5 ), potassium (K₂O), and sililcate (SiO₂) were applied at rates of 75~150 kg ha -1 , 70~86 kg ha -1 , 75~86 kg ha -1 , and 7.5 Mg ha -1 respectively and lime was applied to neutralize soil acidity until 6.5. Average Electrical Conductivity (EC) of soil solution in NPKCLS and NPKC ranged from 1.16 to 2.00 dS m -1 . The NH4+ and K+ levels in NPKCLS and NPKC were higher than that of the other treatments, due to high supply power of rice straw compost. The content of H₃SiO₄ - was higher in NPKCLS because of silicate application. The dominant ions in soil solution were Ca 2+ , Mg 2+ and Na + among cations and HCO₃ - , SO₄ 2- , and Cl - among anions in all treatments. The continuous application of inorganic fertilizers plus rice straw compost (NPKC) and silicate fertilizer (NPKCLS) led to the changes of various chemical composition in soil solutions. Also, they had a significant impact on the improvement of rice inorganic uptake and grain yield. Especially, inorganic uptake by rice in NPKC and NPKCLS significantly increased than those in NPK plot; 14~46% for T-N, 32~36% for P, 43~57% for K, and 45~77% for Si. Therefore, the combined application of inorganic fertilizers with organic compost as a soil amendment is considered as the best fertilization practice in the continuous rice cropping for the improvement of crop productivity and soil fertility.