Tuber Yield Of Sweet Potato Research Articles

Effects of Biochar and Poultry Manure Amendments on Soil Physical and Chemical Properties, Growth and Sweet Potato Yield in Degraded Alfisols of Humid Tropics

Information on the impact of biochar and poultry manure on soil characteristics and sweet potato productivity in the humid tropics is lacking. Hence, field experiments were conducted at two locations during the 2019 and 2020 cropping seasons to assess the effects of biochar (B), poultry manure (PM), and their mixture on soil physical and chemical properties, growth and tuber yield of sweet potato (Ipomoea batatas L.) Each year, the experiment consisted of 4 × 3 factorial combinations of biochar (0, 10.0, 20.0 and 30.0 t ha-1) and poultry manure (0, 5.0 and 10.0 t ha-1). The findings revealed that using B and PM alone, as well as in combination, improved soil physical and chemical qualities, as well as sweet potato performance. Significant interactions of B and PM (B × PM) were observed on soil characteristics and sweet potato variables that were measured in both years, showing B’s potential in enhancing PM use efficiency. Pooled over two years, application of the highest dosage of 30.0 t ha-1 B + 10.0 t ha-1 PM significantly increased tuber yield of sweet potato compared with other treatments. The multiple regressions showed that both soil physical (bulk density, porosity and moisture content) and chemical (pH, OC, TN, P, K, Ca, and Mg) properties had a significant impact on sweet potato leaf area and tuber yield. The findings indicated that B and PM have the ability to improve soil quality and sweet potato production. Keywords: Biochar; Poultry manure; Soil properties; Sweet potato; Alfisols

The Effect of Eliminating the Application of Phosphorus-Containing Fertilizer for the Bulking Period of Sweet Potato (Ipomoea batatas) Production

The Philippine Root Crop Research and Training Center (PhilRootcrops) divided fertilizer applications for sweet potato farming into various phases. Full fertilizer is applied two weeks after planting for the vegetative growth period. Apply another set of fertilizers containing a combination of nitrogen and potassium during the bulking period one and a half months later; this is one way to give the tuber a sweetened flavor. Because fresh sweet potato tubers are more marketable if their sizes are more or less consistent, the study hypothesized that ceasing to apply fertilizer containing phosphorus will adversely affect the uniformity of the size of sweet potato tubers. The application of mixtures of muriate of potash and urea-containing fertilizer increased sweet potato tubers with the highest average circumference and the average weight in Treatment 2 [Circumference (C)=12.4 cm; weight (W)=0.35 kg], which demonstrates the elimination of phosphorus-containing fertilizer for the bulking period of sweet potato production. According to the one-way analysis of variance (ANOVA) and F test (F = 1.09, p = 0.41), there was no statistically significant difference in the dependent variable between the various groups. The study finds that using muriate of potash and urea-containing fertilizer combinations generated the maximum yield in terms of circumference and weight per tuber for sweet potato farming with semi-loam varieties (Treatment 2). The usual application of the farmers under study to Treatment 2 is to reduce the use of synthetic fertilizers. Based on the study results, phosphorus-containing fertilizer does not affect sweet potato tuber yield.

Yield and Profitability of Sweet Potato (Ipomoea batatas (L.) Lam) as a Function of Increasing Levels of Phosphorus and Varieties in Southern Ethiopia

Sweet potato is among the most important food security crops in Ethiopia. However, its productivity is constrained by poor soil fertility and a lack of improved varieties. A field experiment was conducted to evaluate the growth and yield response and profitability of three sweet potato varieties to rates of phosphorus (P) in Southern Ethiopia. Five rates of P (0, 10, 20, 30, and 40 kg ha−1) and three sweet potato varieties (Awassa-83, Kulfo, and Local) were considered as treatments that were laid out in a randomized complete block design with three replications. The vine length, internodes length, diameter, and the number of vines were significantly varied among varieties while P had a nonsignificant effect on these parameters. The tuber yield of sweet potato was influenced by the combined effect of variety and P rate. The highest marketable yield (30.22 t ha−1) was obtained at 30 kg P ha−1 from variety Awassa-83 and the lowest marketable yield (6.57 t ha−1) was obtained from Kulfo at 0 kg P ha−1. Thus, improvement of sweet potato productivity in the study area could be achieved through the use of Awassa-83 variety with P at a rate of 10 kg ha−1.

Soil properties, sweet potato growth and yield under biochar, poultry manure and their combination in two degraded Alfisols of humid tropics

Information on the impact of biochar and poultry manure on soil characteristics and sweet potato productivity in the humid tropics is lacking. Hence, field experiments were conducted at two locations during the 2019 and 2020 cropping seasons to assess the effects of biochar (B), poultry manure (PM), and their mixture on soil physical and chemical properties, growth and tuber yield of sweet potato (Ipomoea batatas L.) Each year, the experiment consisted of 4 × 3 factorial combinations of biochar (0, 10.0, 20.0 and 30.0 t ha−1) and poultry manure (0, 5.0 and 10.0 t ha−1). The findings revealed that using B and PM alone, as well as in combination, improved soil physical properties, increased soil chemical qualities, and sweet potato performance. Significant interactions of B and PM (B × PM) were observed on soil characteristics and sweet potato variables that were measured in both years, emphasizing B's potential in enhancing PM use efficiency. Pooled over two years, application of the highest dosage of B at 30.0 t ha−1 and PM at 10.0 t ha−1 (B30+PM10) significantly increased tuber yield of sweet potato by 108, 147, 196, 89, 124 and 220%, compared with sole B at 30.0 t ha−1 (B30+PM0), sole B at 20.0 t ha−1 (B20+PM0), sole B at 10.0 t ha−1 (B10+PM0), sole PM at 10.0 t ha−1 (B0+PM10), sole PM at 5.0 t ha−1 (B0+PM5) and the control (B0+PM0), respectively. The findings indicate that B and PM have the ability to improve soil quality and sweet potato productivity.

Organic Amendments Influence the Yield of Vegetables and Soil Properties at Charlands in Bangladesh

The field experiment was conducted in the Charlands of Bangladesh during November 2021 to March 2022 to find the crop production and soil properties status. A randomized complete block design was followed with six treatments and three replications. The organic amendments were quick compost, standard organic fertilizers, poultry manure and biochar @ 3t/ha. A positive change was found for the application of manures compared to control plot with the crop production and soil fertility status from our experimental findings. The yield per plant of pumpkin was ranged from 27.24 to 85.61 kg and BCR 1.06 to 3.40. The fresh tuber yield of sweet potato was varied from 39.29 to 94.00 t/ha and BCR 1.20 to 3.54. Soil pH was varying from 6.74 to 7.36, OC from 0.69 to 1.82%, total N from 0.074 to 0.145%, available P from 7.49 to 17.66mg/kg, available S from 9.55 to 17.81mg/kg and Zn from 0.536 to 1.134mg/kg. Biochar treated plot showed the best result compered to others. Organic amendments should be recommended in the farmer’s field for better crop production and soil fertility status.

Benefits of biochar, poultry manure and biochar–poultry manure for improvement of soil properties and sweet potato productivity in degraded tropical agricultural soils

Studies on the effects of biochar and poultry manure on soil properties and sweet potato productivity are scarce. Hence, field experiments were conducted during 2019 and 2020 cropping seasons at two sites to evaluate the effects of biochar (B), poultry manure (PM) and their combined application on soil physical and chemical properties, growth and tuber yield of sweet potato (Ipomoea batatas L.). Each year, the experiment consisted of 4 × 3 factorial combinations of biochar (0, 10.0, 20.0 and 30.0 t ha −1) and poultry manure (0, 5.0 and 10.0 t ha −1). The experiment was laid out in a randomized complete block design with three replications. The results showed that combined application of B and PM improved soil physical and chemical properties, growth and tuber yield of sweet potato better than sole application of B and PM. In both years, there were significant interactions of B and PM (B × PM) on soil properties and sweet potato variables that were measured, indicating the potential of B in improving nutrient use efficiency of PM amendment. It was found that the highest application rate of 30.0 t ha −1 B and 10.0 t ha −1 PM (B30+PM10) gave the highest tuber yield of sweet potato at both sites. Averaged over two years, the highest application rate of B at 30.0 t ha −1 and PM at 10.0 t ha −1 (B30+PM10) significantly increased tuber yield of sweet potato by 108, 147, 196, 89, 124 and 220%, compared with sole B at 30.0 t ha −1 (B30+PM0), sole B at 20.0 t ha −1(B20+PM0), sole B at 10.0 t ha −1 (B10+PM0), sole PM at 10.0 t ha −1(B0+PM10), sole PM at 5.0 t ha −1(B0+PM5) and no application of B or PM (control) (B0+PM0), respectively. Lowest tuber yield was obtained for the control. The multiple regressions revealed that bulk density, porosity and moisture content and soil chemical properties (pH, OC, N, P, K, Ca and Mg) significantly influenced the tuber yield of sweet potato and therefore dictated the performance of sweet potato in Alfisols of southwest Nigeria. The highest application rate of 30.0 t ha −1 B and 10.0 t ha −1 PM were found best on most of the measured soil physical and chemical properties, growth and tuber yield of sweet potato. The results indicated that B in combination with PM have the potential to improve soil properties and sweet potato yield of severely degraded soils.

A New Curve of Critical Leaf Potassium Concentration Based on the Maximum Root Dry Matter for Diagnosing Potassium Nutritional Status of Sweet Potato.

Critical leaf nutrient concentrations have often been used to diagnose the nutritional status of crops. Determining critical leaf potassium (K) concentrations for the maximum root dry matter (RDM) will provide a reliable means of linking leaf K nutrient concentrations to the yield of sweet potato. Three field experiments, using varying K application rates (0–300 kg K ha−1) and two sweet potato cultivars, were performed in the Zhejiang Province of China. A new critical leaf K curve (Kleaf) based on the maximum RDM was determined to assess K nutrition in sweet potato and described by the equation . A critical root K curve (Kroot) based on the maximum RDM was also determined to assess K nutrition and described by the equation . The K nutrition index (KNI) was constructed to identify the situations of K-limiting and non-K-limiting treatments. The leaf KNI (KNIleaf) ranged from 0.56 to 1.17, and the root K KNI (KNIroot) ranged from 0.52 to 1.35 during the growth period of sweet potato. The results showed that the critical leaf K concentration curve can be used as an accurate leaf K status diagnostic tool at critical growth stages that connected leaf nutrient concentration and sweet potato tuber yield. This K curve will contribute to K management of sweet potato during its growth period in China.

English

Leaf harvesting of sweet potato during vegetative stage is common in most parts of Liberia. There is little information on the effects of severity of apical shoot harvesting on tuber yield of sweet potato. Experiments were conducted in 2017 at the Federal University of Agriculture, Abeokuta to determine the effects of severity of apical shoots harvest on growth and tuber yields. Experiment consisted of two varieties (SHABA and SPK-004) and three levels of cutting severity; no cutting, cutting of 15 and 30 cm long apical shoots at 4-weeks. Treatments were arranged in split plot with variety as the main plot and cutting severity as sub-plot arranged in (RCBD) with three replications. Data were collected on vine length, number of leaves per plant, number of branches per plant, leaf area, and leaf area index, fresh and dry apical shoots weight, tuber, unmarketable yield, marketable yield and total number of tuber. Data collected on growth, yield parameters were subjected to  analysis of variance and mean values separated using standard error at (p<0.05). In cutting severity, vegetative growth and tuber yield of SHABA were significantly higher than those of SPK-004. Cutting at 15 cm long apical shoots gave higher total tuber yields in SHABA than SPK-004. Cutting at 30 cm long apical shoots increased fresh apical shoot weigh in SPK-004 than in SHABA. For SHABA and SPK-004 had more tuber weight than 30 cm long apical shoots. Therefore, sweet potatoes whose apical shoot was cut at 15cm long for 4 weeks are recommended.      Key words:  Bacterial blight, disease development, grain yield, planting densities, percentage severity index.  

Sweet potato (<i>Ipomoea batatas</i>) growth and tuber yield as influenced by plant spacing on sandy loam in humid tropical environment

The choice of appropriate plant spacing that gives optimum density of sweet potato (Ipomoea batatas (L.) Lam) is crucial for its productivity, considering that plant density of cover crops affects above-ground access to sunlight, degree of soil surface cover, and below-ground tuberization. The influence of plant planting and the ensuing plant density on growth and tuber yield of sweet potato in a sandy-loam soil in southern Nigeria was assessed in the 2012 and 2013 growing seasons. The field trials involved five plant spacings namely 90 × 90, 60 × 90, 60 × 60, 30 × 90, and 30 cm × 60 cm; corresponding to plant densities of 1.23, 1.85, 2.78, 3.70 and 5.56 plants m–2, respectively. Data were collected on vine girth, number of leaves, leaf area, tuber weight plant–1 and tuber yield, as well as on weed dry matter. Closer plant spacings resulted in higher number of leaves m–2 and leaf area index (LAI). However, tuber weight plant–1 was highest with the second widest spacing (60 cm × 90 cm) and decreased with spacing. By contrast, tuber yield increased with spacing; the closest spacing (30 cm × 60 cm) gave the highest value (12.95 t ha–1) which, however, was similar to 10.55 t ha–1 due to the second closest spacing (30 cm × 90 cm) which, in turn, was similar to 60 cm × 60 cm (9.55 t ha–1) and 60 cm × 90 cm (8.89 t ha–1). Tuber yield correlated with number of leaves (r = 0.57*) and LAI (r = 0.54*), suggesting that the increases in these growth variables due to denser plant population translated into greater photosynthetic activity and translocation of assimilates to the tubers, which manifested as increased tuber yield. Spacing had no influence on weed dry matter. Sweet potato growers on well-drained sandy loam and similar soils in the humid tropics should consider adopting 60 cm × 90 cm with ‘intercropping’ to maximize space and resource use. Alternatively, they should space sweet potato 30 cm × 90 cm in sole production to achieve the desired density (3.70 plants m–2) for optimizing resource use and tuber yield. Key words : leaf area index, number of leaves, tuber weight per plant, optimum tuber yield, sweet potato

Determination of Fertilizer Doses of Sweet potato (Ipomoea batatas L.) “Rancing”

Nitrogen, phosphorus, and potasium availability are the most thresholding factors for maximum growth and yield. The tuber yield of sweet potato varies depending on growing area therefore a fertilization program, especially in the type and the dose of the fertilizers, is required. This research was conducted in the Pasir Muncang experimental farm at Gadog, Bogor, West Java, Indonesia. The study site is located ±500 meters above sea levels, 6°39’31.90” south latitude and 106°52’7.77” east longitude. The experiment was started in May to September 2017. Multi nutrient response method was used for this study, and the interpretation of the results was used to develop fertilizer recommendations using single-nutrient quadratic model. The recommendation was determined using N, P2O5, K2O fertilizer response curve, where the first recommendation was calculated from the maximum relative yield,and the second, third, and fourth recommendation were determined from N, P2O5, K2O threshold. Each treatment for N, P and K was evaluated with different level of fertilizer dose using a randomized complete block design with three replications. The fertilizer doses were 50, 100, 150 and 200% from reference (100% N = 100 kg N ha-1, 100% P = 75 kg P2O5 ha-1, dan 100% K = 100 kg K2O ha-1). Relative yield of sweet potato (y), response to fertilizer (x) had improvement quadratically with equation y = -0.0017x2 + 0.538x + 40.035 for N, y = -0.0041x2 + 0.8595x + 38.211 for P2O5, and y = -0.0025x2 + 0.4318x + 73.377 for K2O. The optimized dose of fertilizer to get maximum yield of sweet potato tuber is 158.23 kg ha-1 of N, 78.60 kg ha-1 of P2O5, and 83.60 kg ha-1 K2O, or 343.97 kg ha-1 of Urea, 218.53 kg ha-1 of SP36 139.33 kg ha-1 of KCl.Keywords: multi nutrient response, nitrogen, relative yield, phosphorus, potassium

Effects of Application of Farmyard Manure and Inorganic Phosphorus on Tuberous Root Yield and Yield Related Traits of Sweet Potato [Ipomoea batatas (L.) Lam] at Assosa, Western Ethiopia

Sweet potato is one the most important root crops produced in western Ethiopia. However, the yield is far below its genetic potential. Lack of recommendation on appropriate rates of fertilizers is one of the problems limiting yield. A study was conducted to determine the effect of application of farm yard manure and inorganic phosphorus on tuberous root yield and yield related traits of sweet potato at Assosa from July to December 2016. The treatment consisted of four levels of farm yard manure (0, 5, 10 and 15 t ha-1) and four levels of P (0, 23, 46 and 69 kg P2O5 ha-1). The experiment was laid out as a Randomized Complete Block Design in a factorial arrangement and replicated three times. Analysis of the results showed that the main effect of farm yard manure significantly (P<0.05) affected most of the traits studied. The interaction effects of the two also affected most of the growth as well as yield parameters considered. Application of combinations of 15 t ha-1 farm yard manure and the highest rate of P2O5 resulted in 39.3% faster in bud sprouting. The main effects of farm yard manure affects tuber diameter (20.63 cm), unmarketable tuber yield (1.3 t ha-1), weight of tuber/plant (143 g), weight of marketable tuber/plant (140 g), dry matter content (27.04), specific gravity (1.12), length of tubers(15.68 cm). The highest vine length (139.67 cm), total tuber number per plant (8.0), total tuber yield (24.6 t ha-1), marketable tuber yield (23.65 t ha-1) was recorded at 15 t ha-1 farm yard manure+69 kg P2O5 ha-1 whereas the lowest vine length (45.3 cm), tuber number per plant (2.0), total tuber yield (5.52 t ha-1), marketable tuber yield (3.61 t ha-1) was recoreded at un amended control. The main effects of farm yard manure delayed maturity of the crop where the 15 t ha-1 farm yard manure showed delay by about 18 days. Moreover, tuber diameter, length of roots, and weight of tuberous roots exhibited improvement with increment in the amount of applied farm yard manure while none of these parameters were affected by the application of P2O5 fertilizer. From this study, the highest net benefit for tuber yield of sweet potato was recorded from the application of manure and P2O5 at the combination level of 15 t ha-1 farm yard manure+69 kg P2O5 ha-1 which was 57873 Birr ha-1. Therefore, the doses of 15 t farm yard manure ha-1 and 69 kg P2O5 ha-1 could be integrated and applied for sweet potato crops in the study area. However, it warrants further testing to give conclusive recommendation.

Study into tillage-mulch package for production of sweet potato (Ipomoea batatas L) effect on soil properties and yield

Field experiments were carried out during 2014 cropping season at Omuo-Ekiti and Kabba. Omuo falls within the forest zone while Kabba is in the southern guinea savanna zone of Nigeria. The experiment at the two sites was to study the effect of tillage and mulch combinations on soil physical and chemical properties and sweet potato (Ipomoea batatas L.) performance. The trial consisted of 2 x 5 factorial combinations of two tillage methods: no-tillage (NT) and manual tillage (MT) and five levels of mulch, siam weed (Chromolaena odorata), {0, 5, 10, 15 and 20 t/ha}.These were laid out using split plots design arranged in a randomized complete block with each treatment replicated four times. There were no significant differences in the values of soil moisture content, soil temperature, porosity and bulk density between Omuo and Kabba sites. Omuo site has significant values of soil organic matter (SOM), total N, K and sweet potato tuber yield compared with Kabba site. Omuo has 1.8 t/ha (10%) higher sweet potato yield compared with Kabba. No-tillage treatment has higher soil moisture content, SOM, N, P, K, Ca, Mg and higher tuber yield compared with manual tillage, The yield difference between NT and MT was 2.9 t/ha (16.7%). Application of mulch increases the yield components of sweet potato compared with no mulch application. The increase in yield as mulch rates increases was adduced to increase in soil organic matter from the mulch. There were however no significant differences between 15 and 20 t/ha mulch levels. Mulch applied at 15 t/ha was found to be suitable for sweet potato in tropical Alfisol. Therefore for soil fertility conservation and performance of sweet potato, no-tillage and 15 t/ha siam weed mulch is recommended.

Comparative Effect of Organic and In-Organic Fertilizer Treatment on the Growth and Tuberyeild of Sweet Potato (Ipomea Batata L)

The experiment was conducted at the teaching and Research farm of the Federal University Wukari Taraba State, Nigeria to assess, evaluate and compare the effect of organic fertilizers such as poultry manure, cow dung, organic manure and in-organic fertilizers such as NPK and urea on the growth and tuber yield of sweet potato. The recommended rates of cow dung (10t/ha) poultry manure (10t/ha), organic manure (10t/ha) NPK15:15:15 (400kg/ha) and urea (200kgN/ha) were applied as treatment to sweet potato with a control at (0kg/ha). These were arranged in a randomized complete block design with three replications. Measurement were taken on the growth and tuber yield at harvest such as the length of primary vein, number of secondary vein number of leaves, number of tuber and tuber weight. Data collected were analyzed using (ANOVA) and the significant means separated using Duncan multiple difference at 5% probability level. The result revealed or showed that numbers of leaves were significant in all the treatments. Application of urea fertilizer produced the highest number of tuber per plant, while tuber weight was not significantly different, but poultry manure application had the higher mean value of (2.34kg). It was concluding that application of poultry manure as organic fertilizer are better and can compare readily with inorganic fertilizer (urea) in the production of sweet potato.

Differences in transport of photosynthates between high-and low-yielding Ipomoea batatas L. varieties

Previous studies have focused mainly on the accumulation of photosynthates and less on their distribution in sweet potato (Ipomoea batatas L.). In addition, the effect of photosynthate accumulation in root tubers on photosynthate distribution was not considered. Thus, a field experiment was carried out from May to October (2011 and 2012) to clarify the differences in photosynthate transport between high- and low-yielding sweet potato. This study mainly focused on the photosynthetic capacities of leaves, photosynthate distribution, and characteristics of photosynthate accumulation in root tubers. Results showed the high-yielding varieties displayed the higher fresh root tuber yield and the economic coefficient than the low-yielding varieties. They also showed greater net photosynthetic rate with a pronounced increase at the early and middle growth stages (8.9% and 11.4%, respectively). After the growth peak, the leaf area index (LAI) of the high-yielding varieties decreased with time and was maintained at 2∼3 until harvest, whereas the LAI of the low-yielding varieties decreased slowly. The high-yielding varieties reached the 13C distribution rate ≥ 50% at the early (2011, 2012) and middle (2011) growth stages, whereas the low-yielding varieties reached it at the late (2011) or middle (2012) growth stages. At harvest, the 13C distribution rates in the branches and root tubers of the high-yielding varieties were 6.0–20.3% and 73.7–91.2%, respectively, whereas those of the low-yielding varieties were 29.6–34.7% and 60.7–63.5%, respectively. The high-yielding varieties showed the remarkable initial potential in root tubers, which was much better than that of the low-yielding varieties. The high-yielding varieties also produced heavier root tubers and the higher number of root tubers per plant at the early bulking stage. The root tubers also attained the greater content of soluble sugar and starch. The high-yielding varieties formed root tubers earlier, showed strong abilities to transport photosynthates into the root tubers, and exhibited a higher mean accumulation rate. These varieties could also reduce the photosynthate consumption in branch leaves and stems. Therefore, the high-yielding varieties established growth advantage for the root tubers earlier. It contributed to a reasonable distribution structure of photosynthates that led to the high root tuber yield. Based on our results, effective agricultural measures can be chosen to improve the root tuber yield of sweet potato.

Biochars influence sweet‐potato yield and nutrient uptake in tropical Papua New Guinea

AbstractCurrently, the biomass of an invasive and obnoxious weed, kunai grass (Imperata cylindrica), is uncontrollably burnt in Papua New Guinea in subsistence farming systems resulting in unwarranted negative environmental consequences. We explored the possibility of sustainable utilization of biochar produced from the weed biomass along with a standard feedstock‐rice husk (Oryza sativa). Biochars were produced with lab‐scale pyrolysis at 550°C, characterized for chemical properties and plant nutrient composition. Further, agronomic efficacy of soil incorporation of biochars (5 t ha−1) or co‐applied with mineral fertilizers (100, 11, and 62 kg ha−1 N, P, K, respectively) was tested for sweet potato (Ipomoea batatas L. Lam) in a field experiment. The two biochars differed significantly (P &lt; 5%) with respect to recovery from the feedstocks, chemical characters and nutrient composition. Kunai grass biochar was poorer in nutrients (&lt; 1%) with distinctly alkaline pH and higher electrical conductivity. Biochar amendment to soil showed significant (P &lt; 5%) improvement of soil moisture, while co‐application of biochars along with mineral fertilizers showed soil moisture decrease. Biochar amendment improved the growth parameters and total tuber yield of sweet potato by about 20%, while co‐application with mineral fertilizers augmented total tuber yield by 100% and above‐ground biomass yields by &gt; 75%. Besides, improving agronomic performance of sweet potato crop, co‐application of biochars with mineral fertilizers enhanced uptake of N, P, K, Ca, Mg, and S. Production and utilization of biochar in sweet‐potato production could offer an efficient means of disposing biomass of kunai grass with concomitant productivity improvement in Papua New Guinea.

Hybrid maize and sweet potato intercropping: a technology to increase productivity and profitability for poor hill farmers in Bangladesh

The experiment was conducted at the Hill Agricultural Research Station, Khagrachari during two winter seasons of 2010-11 and 2011-12 to find out suitable planting system of the component crops for increasing productivity and profitibility for hill farmers of Bangladesh. Three intercrop combinations viz., (i) maize paired row + 2 rows sweet potato, (ii) maize normal row +1 row sweet potato and (iii) sweet potato normal row + 1 row maize were evaluated against their respective sole crops. In all combinations, light availability was more at early growth stage and reduced gradually with the advancement of canopy development of maize. Light availability was minimum at 100 days after emergence and thereafter slightly increased in three intercrop combinations. Among intercrop combinations, light availability to sweet potato canopy was more in maize paired row + 2 rows sweet potato combination through out the crop period which enhance tuber formation, tuber bulging and tuber yield. Contrary, sweet potato vines provide a mulch cover for maize which preserve soil moisture and reduce weed infestation producing higher yield and yield components of maize. Maize yield (cob yield: 19.82 t ha-1, grain yield: 8.98 t ha-1), tuber yield of sweet potato (17.11 t ha-1) and maize equivalent yield (cob equivalent yield: 42.63 t ha-1, grain equivalent yield: 15.82 t ha-1) were the highest in maize paired row + 2 rows sweet potato combination. Similarly, the highest gross return (for cob: Tk. 1,27,890 ha-1, for grain: Tk. 1,58,200 ha-1), gross margin (for cob: Tk. 87,890 ha-1, for grain: Tk.1,08,200 ha-1) and benefit cost ratio (for cob: 3.20, for grain: 3.16) were also obtained from the same combination. The results revealed that maize paired row + 2 rows sweet DOI: http://dx.doi.org/10.3329/sja.v12i2.21922 SAARC J. Agri., 12(2): 101-111 (2014)

Long-Term Effect of Lime, Mycorrhiza, and Inorganic and Organic Sources on Soil Fertility, Yield, and Proximate Composition of Sweet Potato in Alfisols of Eastern India

A field experiment was conducted for five kharif seasons (2006–2011) in an Alfisol to study the effect of integrated use of lime, mycorrhiza, and inorganic and organics on soil fertility, yield, and proximate composition of sweet potato. Application of graded doses of nitrogen, phosphorus, and potassium (NPK) significantly increased the mean tuber yield of sweet potato by 44, 106, and 130 percent over control. Green manuring along with ½ NPK showed greater yield response over that of ½ NPK. The greatest mean tuber yield was recorded due to integrated application of lime, farmyard manure (FYM), NPK, and MgSO4 (13.69 t ha−1) over the other treatments. Inoculation of mycorrhiza combined with lime, FYM, and NPK showed a significant yield response of 10 percent over FYM + NPK. Conjunctive use of lime, inorganics, and organics not only produces sustainable crop yields but also improve soil fertility, nutrient-use efficiency, and apparent nutrient recovery in comparison to NPK and organic manures.

Effects of Plastic Film Mulching Cultivation on Young Roots Growth Development, Tuber Formation and Tuber Yield of Sweet Potato

A two-year trial and a one-year pot experiment were performed to investigate growth and development and absorbing ability of young roots, endogenous hormones content of differentiated roots at early growing stage using variety Jixu 23 with two types of plastic film mulching cultivation, and no plastic as control(CK). The tuberous root fresh weight per plant at 50 days after planting was determined, and its relationship with tuberous root yield at harvest time was analyzed. The results showed that, at 10 and 20 days after planting, the number, total length, fresh weight, and volume of young roots significantly increased compared with control, and the differences in activity, total absorption area and active absorption area of young roots between two plastic film mulching treatments were significant(P0.05), showing the black plastic film mulching(BF) superior to the transparent film mulching(TF). Besides, zeatin riboside(ZR) content of differentiated roots(at 10 and 20 days after planting) was significant improved, which was in favor of procambium activity and tuberous roots formation. On the other hand, at early expansion period of tuberous roots, plastic film mulching cultivation increased abscisic acid(ABA) content and decreased gibberellin(GA) content in differentiated roots, as well as improved the secondary cambium activity, starch accumulation and differentiated root expansion. Meanwhile, abscisic acid(ABA) content and gibberellin(GA) content under the black film mulching significantly changed. Film mulching cultivation increased the number and fresh weight of tuberous roots per plant at 50 days after planting, which contrib-uted to higher fresh yield of tuberous root at harvest time. In the two year experiment, two treatments significantly enhanced the valid tuber number and fresh tuber yield compared with CK. The average increments were 10.71% and 5.76% in 2011, and 12.99% and 7.45% in 2012, respectively.

Evaluation of sweet potato (Ipomoea batatas L.) performance and soil&lt;br&gt;properties under tillage methods and poultry manure levels

Research study on the effect of tillage systems and application rate of poultry manure on sweet potato (Ipomoea batatas) in Alfisol of southwest Nigeria is lacking. Field trials were conducted in 2006, 2007 and 2008 cropping seasons on an Alfisol (Oxic Tropuldalf) at Owo in rainforest zone of southwest Nigeria. The trials consisted of the factorial combinations of two tillage methods (manual clearing and conventional tillage) and four manure levels (0, 5, 10 and 15 t/ha) arranged in a randomized complete block design and replicated three times. Conventional tillage alone (CTo) resulted in lower soil N, P, K, Ca, Mg and soil organic C and better leaf N, P, K, Ca and Mg concentrations, growth and yield of sweet potato compared with manually cleared (MCo) plots. The better performance of sweet potato under conventional tillage (CTo) was adduced to reduced bulk density. Bulk density was negatively correlated with yield. Conventional tillage alone (CTo) improves sweet potato tuber yield by 62, 55 and 42% in 2006, 2007 and 2008, respectively compared with manual clearing alone (MCo). In both the manually cleared and conventionally tilled plots, soil organic C, N, P, K, Ca, Mg and water content increased with amount of poultry manure, while soil pH, bulk density and temperature were reduced. Yields given by 5, 10 and 15 t/ha poultry manure were not significantly different under both manually cleared and conventionally tilled treatments. Conventional tillage plus 5 t/ha poultry manure (CT+5 PM) produced the highest overall yield. Compared with manual clearing alone (MCo) and conventional tillage alone (CTo), conventional tillage plus 5 t/ha poultry manure (CT+5 PM) improved tuber yield of sweet potato by 117 and 43%, respectively. Therefore the use of 5 t/ha poultry manure with conventional tillage is recommended for sweet potato production on an Alfisol of southwest Nigeria.

Tillage and fertilizer effects on some soil properties, leaf nutrient concentrations, growth and sweet potato yield on an Alfisol in southwestern Nigeria

Tillage and fertilizer influenced soil characteristics through their effects on soil properties which in turn affect crop performance. Field experiments were conducted during 2006 and 2007 cropping seasons on an Alfisol (Oxic Tropuldalf) at Owo in the forest-savanna transition zone of Nigeria to evaluate the effect of tillage and fertilizer types on soil properties and sweet potato yield ( Ipomoea batatas L.). Two tillage treatments namely: zero tillage (ZT) and conventional tillage (CT) were combined with each of NPK-15-15-15 fertilizer at 250 kg ha −1, poultry manure (PM) at 10 t ha −1, combined application of 125 kg ha −1 NPK 15-15-15 fertilizer + 5 t ha −1 poultry manure and a control (no fertilizer/manure). The experiment was laid out on a randomized complete block design in a factorial combination of eight treatments that were replicated three times. The surface soil (0–15 cm depth) was chemically analysed before and after crop harvest and some selected soil physical properties, leaf nutrient concentrations, growth and sweet potato yield were determined. Conventional tillage plots had significantly lower soil bulk density (1.30 Mg m −3) than zero tillage plots and resulted in higher leaf N, P, K, Ca and Mg and tuber yield of sweet potato compared with zero tillage. Soil water content was higher, whereas temperature was lower, in zero tillage than conventional tillage. Zero tillage had significantly higher concentrations of soil pH, organic C, N, P, K, Ca and Mg for surface soil (0–15 cm depth). Conventional tillage increased mean tuber yield of sweet potato by 30% compared with planting on untilled zero soil. Application of poultry manure alone and complementary application of NPK fertilizer and poultry manure reduced bulk density and temperature and increased soil water content and porosity, whereas NPK fertilizer did not improve soil physical properties. Compared with control, poultry manure alone, NPK fertilizer alone and complementary application of NPK fertilizer and poultry manure increased soil total N, available P, and exchangeable K, Ca and Mg concentrations as well as leaf N, P, K, Ca and Mg concentrations. Poultry manure tended to improve soil pH, SOC, N, Ca and Mg compared with NPK fertilizer. Combined application of sub-optimal rates of NPK fertilizer and poultry manure gave higher soil and leaf N, P and K concentrations, vine length, vine girth, leaf area and tuber yield compared with NPK fertilizer or poultry manure alone. Compared with control, NPK fertilizer, poultry manure and NPK fertilizer plus poultry manure increased tuber yield by 39, 45 and 83%, respectively. Conventional tillage in combination with NPK fertilizer plus poultry manure gave the highest tuber yield of sweet potato.