Sorghum Cropping System Research Articles

Farmers’ production constraints, preferred varietal traits and perceptions on sorghum grain mold in Senegal

Improving sorghum adoption rates by developing adapted varieties that meet end-user preferences is a major challenge in West Africa. In this study, a participatory rural appraisal was undertaken to identify the main sorghum production constraints, farmers’ preferred variety traits and their perceptions on sorghum grain mold. The study was conducted in four representative rural communities located in the main sorghum producing area of Senegal. A total of 260 farmers were interviewed and data were collected through focus group discussions and individual questionnaires. Our results indicated that Striga, insects, poor soil fertility and drought are the major sorghum producing constraints in Senegal. Grain mold was identified as the second most important sorghum disease after the damping-off. Discoloration on grain surface was the most important criteria farmers used to recognize the disease. The most important sorghum traits farmers desired in improved varieties are medium to short plant maturity cycle, medium plant height, large open or semi-compact panicle, big and white grain, and adaptation to local growing conditions. The results showed that the sorghum cropping system is dominated by male farmers who mainly grow local landraces. These results will provide updated recommendations for the breeding products profile to meet end-user preferences in Senegal.

Carbon footprint of smallholder rain-fed sorghum cropping systems of Kenya: A typology-based approach

Agricultural ecosystems are the main sources of soil-atmosphere exchange (methane-CH4, Carbon dioxide-CO2 and Nitrous oxide -N2O) in sub-Saharan African countries, including Kenya. To feed the ever-growing population, there is a need to identify agricultural management practices to increase food production while reducing GHG emissions for climate change mitigation and adaptation. This study aimed to estimate the GHG balance at the farm scale and identify environmental hotspots and mitigation opportunities among smallholder sorghum farms in Western Kenya. The study hypothesized that different intensification levels influenced the GHG balance. The study collected data from 300 smallholder farms in western Kenya. The principal component analysis and hierarchical clustering analysis were used for farm typologies construction. Five farm types were constructed that ranged from no or minimal external inputs and highly intensified, small to large, and low to highly endowed in tropical livestock units. The Cool Farm Tool Excel program model was used to estimate GHG balances. that the sorghum cropping systems were net sinks of soil GHGs. The GHG balance, carbon footprint, and monetary footprint significantly varied across the farm types at p = 0.025, p = 0.018, and p = 0.004, respectively. The GHG balance ranged from – 818.76 kg CO2 eq. ha−1 in manure-intensive and low fertilizer-intensity small farms to 174.29 kg CO2 eq. ha−1 in fertilizer-intensive and moderate manure application rates on small farms. Fertilizer production and direct and indirect emissions (fertilizer application) were the environmental hotspots accounting for 63 and 30 % of the GHG emissions. The carbon and monetary footprints ranged from -1.29 to 0.45 kg CO2 eq. kg sorghum −1 and -2.02 to 0.13 kg CO2 eq. US$−1 generated, respectively. The study established that sorghum cropping systems in Kenya produced limited greenhouse gas emissions.

Evaluation of Pathogenic Potential of Entomopathogenic Nematode <i>Heterorhabditis indica</i> against <i>Helicoverpa armigera</i>

The isolation and identification studies revealed that the EPN isolates from the Sorghum cropping system was Heterorhabditis indica and showed pathogenicity to the third instar larvae of Corcyra cephalonica in laboratory. The pathogenicity studies revealed that mortality in 3rd, 4th and 5th instar larvae of C. cephalonica and H. armigera was highest at 30 IJs/100µl concentration of EPN suspension. The reproduction and multiplication studies revealed that recovery of EPN Infective Juveniles (IJs) was highest in the 3rd and 4th instar larvae of C. cephalonica and H. armigera when infected with EPN isolates from sorghum cropping system.

Soil organic carbon dynamics in multipurpose cropping systems

Diversification of conventional food-based cropping system with multipurpose lignocellulosic crops could increase biodiversity, farmer’s market opportunities, feedstock for biorefineries, though can also imply soil organic carbon (SOC) stock changes, without competing with food production. Sunnhemp ( Crotalaria juncea L.), biomass sorghum ( Sorghum bicolor L.), kenaf ( Hibiscus cannabinus L.), and industrial hemp ( Cannabis sativa L.) are annual high yielding lignocellulosic crops with great potential for their multiple applications. The objective of the present study was to identify the SOC changes when the aforementioned crops are grown during the fallow periods of a conventional maize ( Zea mays L.)-wheat ( Triticum aestivum L.) rotation over five years. For this purpose, the SOC, carbon inputs (i.e. above and belowground residues), soil respiration , and cumulative CO 2 emissions were evaluated. The experiment was carried out in northern Italy (44°30′ N, 11°21′ E) from 2016 to 2021 in a randomized complete block design (n = 4) by adopting conventional field and harvest management practices (i.e. straw removal with hay machineries and alternating conventional with minimum tillage). The SOC stock increased by 7% from 2016 (56 Mg ha −1 ) to 2021 (60 Mg ha −1 ), regardless of the rotation system. Despite one of the highest CO 2 cumulative soil emissions (11 Mg ha −1 , two and three times higher than sunnhemp, kenaf, and industrial hemp, respectively) the rotation including biomass sorghum ended with higher SOC concentration (7.6 g kg −1 ) compared with industrial hemp (7 g kg −1 ) and kenaf (6.9 g kg −1 ), whereas fallow (7.2 g kg −1 ) and sunnhemp (7.1 g kg −1 ) showed intermediate values. The combination of high aboveground residues and high nitrogen fertilizations are deemed to act primarily on SOC level compared with belowground residues. In summary, the crop intensification did not deplete SOC, moreover biomass sorghum cropping system outperformed kenaf and industrial hemp through the decomposition into SOC of higher released residues. The rotation including sunnhemp coupled high SOC levels with low CO 2 emissions, raising interest in the light of its nitrogen fixing ability which can further help reducing the system’s carbon footprint. • Cropping systems with wheat and maize including lignocellulosic crops during the fallow period are presented. • Over five years, the SOC carbon stock increased by 7%, regardless of rotation. • The rotation resulting with the highest SOC concentration included biomass sorghum (7.6 g kg −1 ). • The rotation resulting with the lowest SOC concentration included industrial hemp (7 g kg −1 ), and kenaf (6.9 g kg −1 ). • Aboveground crop residues, reduced tillage and nitrogen fertilization are likely the main drivers influencing SOC.

Survey of Fungal Foliar and Panicle Diseases in Smallholder Sorghum Cropping Systems in Different Agro-Ecologies of Lower Eastern Kenya

Sorghum is a staple food crop and plays a critical role in subsistence farming in Kenya due to its adaptability to marginal agro-ecological zones. However, fungal diseases are among the major biotic constraints of sorghum production, causing over 70% yield loss in susceptible cultivars. Information on the distribution and severity of fungal diseases is important to establish efficient and improved strategies for integrated disease management of sorghum fungal diseases. The aim of this study was to determine the prevalence, incidence, severity and spatial distribution of fungal diseases on sorghum across agro-ecological zones of lower eastern Kenya. A total of 384 smallholder farmers’ fields were surveyed, and in each field, 30 plants were assessed for prevalence and incidence of fungal diseases using a W-shaped pattern to cover the whole field. Sorghum anthracnose was the most prevalent disease (71%), followed by leaf blight (70.18%), rust (68.41%), smut (63.02%), sorghum mildew (55.33%), Alternaria leaf spot (48.39%) and rough leaf spot (46.02%). Disease prevalence, incidence and severity varied among the investigated agro-ecological zones. There was a significant difference (p ≤ 0.05) in fungal disease severity across the investigated agro-ecological zones. Spatially interpolated disease maps showed a high variation in the distribution of various sorghum fungal diseases across the investigated agro-ecological zones of lower eastern Kenya. Morpho-cultural identification revealed the association of Colletotrichum sublineola with anthracnose, Curvularia lunata and Bipolaris cynodontis with leaf blight, Puccinia purpurea with rust, Peronosclerospora sorghi with downy mildew, Alternaria alternata with Alternaria leaf spot, Ascochyta sorghi with rough leaf spot and Sporisorium sorghi with covered kernel smut symptoms. Information obtained in this study will be useful to update knowledge on sorghum fungal diseases and provide a basis for the development of strategies for management and control of the investigated diseases.

The Role of Sorghum Legume Intercroping System in Improving Soil Productivity on Small Holder Farmers in Western Kenya

Declining crops yield in the smallholder farmers cropping systems of sub-Saharan African (SSA) present the need to develop more sustainable production systems. Depletion of essential plant nutrients from the soils have been cited as the main contributing factors due to continues cultivation of cereal crops without application of organic/ inorganic fertilizers. Field experiments to evaluate effect of phosphorus (P) fertilizers, organic and integration of legumes in sorghum cropping systems on soil, available nitrogen (N) and P, were conducted in Busia County of Kenya during the short (SRS) and long rain seasons (LRS) of 2016 and LRS of 2017 respectively. The experiments comprised either soybean, common bean groundnut or sesame grown with sorghum. The design was a split plot in a randomized complete block design. Main plots were fertilizer inputs; Mavuno, FYM or their combination. Subplots comprised of the legume intercrops mentioned above. Application of Mavuno, FYM or their combination resulted in significantly higher legume, sesame crop yields above the control in the second season. Legume crops due to their N-fixation, litter fall and mineralization made availability of P and N. possible. Application of Mavuno, FYM or their combination gave comparable results with respect to the intercrop yields. Since FYM and (Mavuno+FYM) is cheaper than Mavuno, growing either soybean, common bean groundnut or sesame intercropping system with sorghum with application of the above is recommended for improved legume grain yields and soil fertility improvement.

Impact of fertilisers on soil properties and biomass yield under a long-term sweet sorghum cropping system

A continuous long-term field experiment (2008–2018) was conducted in Xinjiang, north-western China, to assess the impact of farmyard manure (FYM) and inorganic fertilisers on the sustainable biomass yield of sweet sorghum cultivar (Xingaoliang No. 3) and soil chemical properties. Seven treatments, associated with nitrogen (N), phosphorus (P), potassium (K), FYM, and their different combination, were compared with the control plot (CK). As a result, the treatments NP, PK, NK, NPK and NPKM significantly increased the average biomass yields by 30–48% over CK. The 12 t/ha FYM per year with NPK (NPKM) increased both the yield and total soluble solids (T<sub>SS</sub>) by 48% and 7.9%, respectively, while the 18 t/ha/year application rate of FYM had an adverse effect on yield. Stem T<sub>SS</sub>, soil available N and K for all treatments decreased while soil organic carbon, soil total salt and the available P for FYM applied treatments increased over the years. The soil pH stabilised at 7.8–8.2 at the end. In conclusion, the 12 t/ha/year of FYM is the most efficient rate for a single application or incorporation with inorganic fertilisers. A more reasonable application rate of N and K fertiliser to increase the yield and irrigation rate to reduce soil salt needs for further investigation.

Soil Organic Carbon and Labile Carbon Pools Attributed by Tillage, Crop Residue and Crop Rotation Management in Sweet Sorghum Cropping System

Labile organic carbon (LOC) fractions are considered as sensitive indicators of change in soil quality and can serve as proxies for soil organic carbon (SOC). Although the impact of tillage, crop rotation and crop residue management on soil quality is well known, less is known about LOC and SOC dynamics in the sweet sorghum production systems in South Africa. This short-term study tested two tillage levels: no-till and conventional-tillage, two crop rotations: sweet-sorghum/winter grazing vetch/sweet sorghum and sweet-sorghum/winter fallow/sweet sorghum rotations and three crop residue retention levels: 30%, 15% and 0%. Tillage was the main factor to influence SOC and LOC fractions under the sweet sorghum cropping system in South Africa. NT increased SOC and all LOC fractions compared to CT, which concurs with previous findings. Cold water extractable organic carbon (CWEOC) and hot water extractable organic carbon (HWEOC) were found to be more sensitive to tillage and strongly positively correlated to SOC. An increase in residue retention led to an increase in microbial biomass carbon (MBC). This study concludes that CWEOC and HWEOC can serve as sensitive early indicators of change in soil quality and are an ideal proxy for SOC in the sweet-sorghum cropping system in South Africa.

Microbial biomass carbon and enzyme activities as influenced by tillage, crop rotation and residue management in a sweet sorghum cropping system in marginal soils of South Africa

Questions on sustainable and appropriate cropping systems for bioenergy sweet sorghum in the smallholder farming sector still exist. Therefore, a short-term experiment was carried out to study the influence of management on microbial biomass carbon (MBC), β-glucosidase, acid phosphatase, and urease activities in a sweet sorghum cropping system in South Africa. Tillage [no-till (NT) and conventional tillage (CT)], rotation [sorghum-vetch-sorghum (S-V-S) and sorghum-fallow-sorghum (S-F-S)] and residue retention [0%, 15% and 30%] were evaluated. Tillage× rotation× residue management interaction influenced (P < 0.05) MBC whilst crop rotation residue influenced (P < 0.05) β-glucosidase. Tillage affected β-glucosidase (P < 0.05), acid phosphatase (P < 0.001), and urease enzyme (P < 0.01) while crop rotation only influenced acid phosphatase (P < 0.01). Residue retention affected acid phosphatase (P < 0.001) and urease enzyme (P < 0.001). NT + S-V-S+30% interaction resulted in the highest MBC content compared to CT + S-F-S+0%. NT+30% enhanced β-glucosidase activity, S-V-S enhanced acid phosphatase compared to S-F-S. MBC and enzyme activities were positively correlated with each other. Tillage and residue management were the main factors influencing soil biological indicators under bioenergy sweet sorghum in South African marginal soils in the short-term. Soil biological indicators were higher under NT and 30% residue retention respectively. NT + S-V-S+30% was a better treatment combination to enhance soil quality under bioenergy sweet sorghum in South African marginal soils.

Interaction between Fusarium head blight and crown rot disease incidence and cultural practices on wheat in the south of Iraq, Basra province

BackgroundThis study was conducted to estimate Fusarium head blight (FHB) and crown rot (FCR) disease incidence on wheat and their interaction with cultural methods (cultivar types, planting time, seed rate, crop rotation, and fertilizer practices) that are used in wheat cropping system in the south of Iraq, Basra province.ResultsThe results showed that the mean average of FHB and FCR was 27.2% and 31%, respectively. This displays that very nearly one-third of wheat crop planted in those 14 fields were infected by both diseases but not very severely, except in two fields (D and HM), which were devastating, 54% and 71% and 41% and 52% for FHB and FCR, respectively. The highest level of incidence for both diseases was associated with the earlier and latest planting dates 28 Oct. and 10 Dec., while the lowest was with 1, 10, and 23 Nov. A 200 and 120 kg/ha were the highest and lowest seed rates used in this study. The selected wheat fields differed in their pre-crop rotations (legume, corn, sorghum, okra, and continuous cropping system of wheat) in a previous year. The amount of added fertilizers (urea, DAP, and NPK) to the studied fields was in a high variation. The seven wheat cultivars examined in this study showed different levels of susceptibility to both diseases.ConclusionThe results verified that most of the agricultural practices examined in this study were associated with positive correlation for FHB and FCR in the occurrence of disease incidence. Except the cultivar type and fertilizer application had unclear relationship with the incidence of both diseases.

Modification of the CERES grain sorghum model to simulate optimum sweet sorghum rooting depth for rainfed production on coarse textured soils in a sub-tropical environment

There is potential to reduce irrigation water requirements in bioenergy feedstock cropping systems by breeding for deep rooted sweet sorghum cultivars that intercept more rainfall water. Such cultivars would require little or no irrigation in some environments. Consequently, the objective of this study was to quantify the potential benefit of deeper rooted sweet sorghum cultivars by simulating a range of root depth and planting date scenarios in the subtropical climate of the southeastern USA by modifying the CERES grain sorghum cropping system model for sweet sorghum. A two year field study was conducted to collect data for model development. The new sweet sorghum model was validated against independent studies from six different locations around the world. The root mean squared error of prediction of the model was 4.7% for days to maturity (6 days), 21% for total biomass weight, and 22.6% for stem dry weight. We then simulated sweet sorghum growth and yield for nineteen hypothetical rooting depths between 30 and 210cm. Based on model simulations, including uncertainty analysis associated with model parameters, the optimal root depth for our environment in the southeastern USA under rainfed conditions, was between 110 and 140cm to maximize final biomass yield. The simulated hypothetical 120cm root depth sweet sorghum had final biomass yields up to 48.2% higher than the simulated widely grown cultivar ‘M81 E’ in rainfed systems and would require up to 32% less irrigation to meet actual evapotranspiration demand. These results highlight the importance of breeding for deeper rooted sweet sorghum cultivars along with optimized sowing dates for higher biomass yields. However, model simulations also indicated that, even with optimal rooting depth and density, irrigation would be needed to maximize final biomass yields.

Long-term bioenergy sorghum harvest strategy and soil quality

A long-term study was initiated in 2008 to determine effects of bioenergy sorghum [Sorghum bicolor (L.) Moench.] production on soil quality. Sorghum biomass removal may potentially deteriorate soil quality and productivity through nutrient removal and decreased organic matter return. Study treatments included continuous bioenergy sorghum and a sorghum/corn (Zea mays L.) biannual rotation, 0, 25, or 50% return of harvested sorghum biomass, no or non-limiting N addition, and a complete nutrient return treatment. The study was conducted near College Station, TX on Weswood silty clay loam soil. Soil quality indicators including soil organic carbon (SOC), total soil nitrogen (TSN), and soil C:N ratio were determined in soil samples collected annually at five depth increments to 90 cm for seven years (2009–2015) and compared to initial values in 2008. The greatest sorghum biomass yield increase from residue return was observed with 25% return and N fertilization. Nitrogen was essential for biomass and biomass C yield for both sorghum cropping systems, especially continuous sorghum. Increasing residue return from 25 to 50% tended to increase SOC in the near surface regardless of N addition, but generally not with depth. From the initial year in 2008 to 2015, SOC increased at all soil depths, except 15–30 cm, under continuous sorghum receiving residue return and N fertilization. Increases in SOC were much higher with continuous than rotated sorghum. For example, SOC storage for fertilized rotated sorghum averaged across residue return rates increased by 10% (59.4 to 65.1 Mg ha−1) and for continuous sorghum by 51% (59.4 to 90.1 Mg ha−1) by 2015 compared to initial values in 2008. For both continuous and rotated sorghum, changes in SOC stocks were greater in lower depths, principally at 30–60 and 60–90 cm, implying that SOC increases at these depths were most likely associated with bioenergy sorghum roots. After seven years of 25% residue return, SOC increased by 1.75, 5.25, 15.4, 32.9, and 39.2 Mg ha−1, respectively, at 0–5, 0–15, 0–30, 0–60, and 0–90 cm. Total soil N to 90 cm depth tended to follow similar patterns as those observed for SOC storage. Soil C:N ratio also tended to increase in all depth increments with residue return, but especially in the surface 0–5 cm with N fertilization. The highest C:N ratio increase were observed in surface soil under continuous sorghum at 25 and 50% residue return rates with or without N fertilization. Increased soil C:N at deeper depths in continuous sorghum was probably associated with sorghum roots. The return of 25% of aboveground biomass from a continuous sorghum cropping system in conjunction with N fertilization appeared feasible for maintaining soil quality in the long term.

On-farm response of groundnut (Arachis hypogaeaL.)-sorghum (Sorghum bicolorL.) cropping system to fertilizers NPK+ FeSO4/ZnSO4input

A field experiment conducted during 2012–13 and 2013–14 at Gadag, Karnataka, India to study on-farm response of groundnut (Arachis hypogaea)-sorghum (Sorghum bicolor) cropping system to fertilizers NPK input revealed that application of 25 kg N, 50 kg P2O5, 25 kg K2O and 25 FeSO4 kg/ha to groundnut and 50 kg N, 25 kg P2O5 0 kg K2O and 15 kg ZnSO4/ha to sorghum recorded significantly higher pod/grain and haulm/stover yields. Groundnut pod equivalent yield (1743 kg/ha), net returns (Rs. 43, 892/ha), benefit: cost ratio (4.58) and total NPK uptake (140.96 kg/ha) by groundnut-rabi sorghum cropping system were also higher in recommended dose of fertilizers (T6) over rest of the treatments. This treatment also recorded the maximum production efficiency (8.11kg/ha/day) and nitrogen use efficiency (32.24 kg/kg) in groundnut and 14.56 kg/kg in rabi sorghum. Response studies indicated that maximum response was noted with NP in groundnut (7.57 kg/kg) and NPK+ZnSO4 in sorghum (8.09 kg/kg).

Effects of Intercrop Population Density and Row Orientation on Growth and Yields of Sorghum - Cowpea Cropping Systems in Semi Arid Rongai, Kenya

Sorghum - cowpea intercropping is an important farming system for small scale farmers in Arid and Semi Arid Lands of sub-Sahara African. Information on the cowpea intercrop population and row orientation effects on growth and yields of sorghum-cowpea cropping systems is however scanty or unavailable for tropical Africa and East African region in particular.With this in mind, a factorial designed experiments was carried out at a farmer’s field at Kampi ya Moto, Rongi, Kenya in two seasons i.e. December 2011 - April 2012 Season I (SI) and May-August 2012 Season II (SII). The treatments comprised of sorghum planted at a constant population of 55 555 plants/ha and intercropped with cowpea at varying populations of 55 555, 111 111, and 166 666 plants/hectare and rows oriented in East-West (E-W) and North-South (N-S) directions, respectively replicated three times. Results showed that increase of cowpea (intercrop) population from 55 555 to 166 666 plants/ha significantly (P ? 0.05) influenced crops growth, grain and yields attributes of both crops. However, there was no significant effect on harvest indices. Intercrop population (cowpea) of 111 111 plants/ha produced the highest cowpea grain yields of 214 and 632 kg/ha in season I and season II, respectively. The highest sorghum grain yields of 2 729 kg/ha and 3 011 kg/ha) were recorded in sole sorghum. The lowest sorghum and cowpea grain yields of 1 994.3 and 147.8 kg/ha were produced by the highest intercrop cropping system population of 166 666 cowpea plants/ha. The E-W row oriented cropping systems produced significantly higher cowpea grain yields ranging from 408 to 973 kg/ha compared to 333 to 838 kg/ha recorded under N-S row orientation. The N-S row orientation however, produced significantly higher sorghum grain yields of 1 874 and 2 123kg/ha from the sole sorghum cropping system in seasons I & II, respectively. It is recommended that farmers in semi-arid Rongai should intercrop sorghum at 55 555 plants/ha with cowpea at 55 555 during the short rainy season of SI (Oct - Dec) and at 111 111 plants/ha during the long rainy SII (May - Aug), season, with rows oriented in the E-W direction, in order to realize over 400 kg/ha cowpea and 2 000 kg/ha sorghum grains yields. The higher cowpea intercrop population of 111 111 plants/ha should be used in wetter seasons of semi arid climates.

한국의 가축 생산성 향상을 위한 유기조사료 생산체계에 관한 연구

Organic forage production system is one of the most important aspects in organic livestock production. Animals in the organic farming system are also essential for manure to be used for organic forage production. Both organic forage and animals are essential to maintain the cycle of organic agriculture system. In this paper we introduce the organic forage production system in Korea. Summer and winter crops are getting popular in Korea because of their high forage yield and cultivation in double cropping systems. Common cropping system for forage production in Korea is the double cropping system with legume and grass mixture. Forage sorghum and sudangrass are the most popular ones of annual summer forage corps because of their high production with low cost in the double cropping systems. In the mixture of forage crops, inter cropping is more suitable in the corn and sorghum cropping system because of high lodging resistance and forage yield, and low weed population. Forage sorghum and sudangrass are difficult to preserve as direct-cut silage due to the fact that its high moisture content causes excessive fermentation during ensiling. Corn grain addition to sorghum silage could be recommended as the most effective treatment for increasing quality and reducing production cost. It is recommended that corn grain could be added up to 10% of total amount of silage. And agriculture by-products also can be added at the time of ensiling to minimize losses of effluent and have the additional advantage of increasing quality. Agriculture by-products as silage supplements increased DM content and quality, and decreased the production cost of sorghum silage. Field pre-wilting treatment of forage crops also increased DM content and quality of the silage. Wilting sorghum×sudangrass hybrid before ensiling was the effective method for reducing effluent and increasing pH and forage quality more than direct cut silage. Optimum prewilting period of sudangrass silage was 1 or 2 days. In organic forage, the most important factor is the enhancement of organic forage sufficiency in relation to the environmental-friendly and organic livestock. Consequently, there are many possibilities for animal production and organic forage production in Korea. No forages no cattle concept should be emphasized in organic farming system.

Soil Carbon Sequestration in Sorghum Cropping Systems

Management practices can influence both the quantity of soil organic carbon (SOC) and its distribution into different fractions or pools. We investigated SOC sequestration potentials of cropping systems in near-surface (0–5 cm) samples through soil size and density fractionation coupled with acid hydrolysis and natural abundance of stable isotopes (δ13C) in a 20-year field study in the southern Great Plains in 2002. Treatments included two tillage regimens, conventional and no tillage (NT), in combination with two cropping systems: continuous grain sorghum [Sorghum bicolor (L.) Moench.] (CS) and a sorghum-wheat (Triticum aestivum L.)-soybean [Glycine max (L.) Merr.] (SWSoy) rotation, and with or without N fertilization. Tillage and cropping sequence significantly affected SOC distribution and the natural abundance of δ13C in different fractions. Samples from CS exhibited δ13C values ranging from −15‰ to −20‰, suggesting most SOC was derived from this C4 crop species. The δ13C values for soils from SWSoy varied from −20‰ to −22‰, reflecting a mixed input from C3-derived and C4-derived residue input. For whole soil and all aggregate-size fractions, SOC concentrations were significantly higher for NT than conventional tillage. However, the effects of cropping system and N fertilization on SOC interacted with tillage. Greater SOC for enhanced cropping (SWSoy) or N fertilization was observed only under NT. The fraction of <53 μm represented a greater proportion of soil than other aggregate-size fractions. Our long-term study indicated that SOC and its various fractions, including more resistant, can be increased by NT with enhanced cropping and N fertilization.

Changes in Soil Chemical Properties in Response to Application of Phosphorus Sources in Legume Sorghum Cropping Systems

Changes in Soil Chemical Properties in Response to Application of Phosphorus Sources in Legume Sorghum Cropping Systems Beldina A. Tunya; Joyce J. Lelei; Josephine P. Ouma; Ombui, P.N; Onwonga, R.N. Abstract Field experiments to evaluate effect of phosphorus (P) fertilizers and integration of legumes in sorghum cropping systems on soil pH, available nitrogen (N) and P, were conducted in Njoro Kenya during the short (SRS) and long rain seasons (LRS) of 2012 and LRS of 2013. The experiments comprised either lupin or chickpea grown with sorghum. The design was a split plot in a randomized complete block design. Main plots were cropping systems; sorghum monocrop, legume - sorghum rotation and legume- sorghum intercrop. Subplots comprised P sources (60 kg P ha- 1); triple super phosphate (TSP) and minjingu phosphate rock (MPR). Application of TSP resulted in significantly higher nutrient concentrations in the soil than MPR addition in the first season. In the second and third seasons, the performance of MPRs approached that of TSP. Legume crops due to their release and accumulation of carboxylic acid lowered the pH to below 5.5 thus making solubilization of MPR and availability of P possible. Intercropping sorghum with lupin or chickpea with application of MPR gave comparable results with use of TSP. Since MPR is cheaper than TSP, growing lupin or chickpea in intercropping system with sorghum with application of MPR is recommended for improved chemical properties. Full Text: PDF DOI: 10.15640/jaes.v3n4a11

Yield Comparison of Nonstructural Carbohydrates in Sweet Sorghum and Legume-Based Cropping Systems

Field experiments were conducted during dry (2009/10) and wet (2010) seasons to evaluate sweet sorghum–legume-based cropping systems for soluble sugars and starch production. Treatments were composed of two types of legumes (mung bean, soybean), two planting patterns (alternate single rows, alternate double rows), and two times of seeding (simultaneous, staggered) together with three monocrop treatments of sweet sorghum, mung bean, and soybean in randomized complete block design. Key observations indicated that the average yields of soluble sugars and starch were significantly reduced in intercropping systems in both seasons, due to partial or interactive influence of treatments considered. Yields of soluble sugars and starch were increased by 6 and 11% in the dry season and by 5 and 19% in the wet season in sweet sorghum–soybean and sweet sorghum–mung bean associations, respectively, when established with staggered seeding compared to those in simultaneously seeded combination or in monocropping of sweet sorghum.

Adubação nitrogenada de sorgo granífero consorciado com capim em sistema de plantio direto

O objetivo deste trabalho foi avaliar o efeito do manejo da adubação nitrogenada sobre a cultura do sorgo granífero, cultivado solteiro e em consócio com capim-marandu e capim-mombaça, e determinar a produtividade de matéria seca das forrageiras, nos anos agrícolas 2003/2004 e 2004/2005, em plantio direto. Foi utilizado o delineamento experimental em blocos ao acaso, em arranjo fatorial 3x5, com quatro repetições. Os tratamentos consistiram de três sistemas de cultivo de sorgo granífero (solteiro e consorciado com capim-marandu ou capim-mombaça, na linha de semeadura) e cinco manejos de adubação nitrogenada: 30-70; 70-30; 50-50; 100-0; e 0-100 kg ha-1 de N, quantidades aplicadas na semeadura e na cobertura, respectivamente. O cultivo consorciado não afetou a nutrição nem a produtividade de grãos de sorgo. Apenas no primeiro ano de cultivo, o parcelamento 50-50 kg ha-1 de N proporcionou maior produtividade de grãos. O manejo da palhada interferiu no estabelecimento do sorgo no segundo ano de cultivo, e diminuiu a produtividade de grãos. As maiores doses de N aplicadas em cobertura elevaram a produtividade de matéria seca do capim-marandu e, as aplicadas em semeadura, a elevaram no capim-mombaça.

Influence of cowpea genotype and sorghum-cropping system on cowpea infestation by some insect pests in the sudan savannah of Nigeria

Field trials were conducted at the International Institute of Tropical Agriculture, Agricultural Research Station at Minjibir, Kano State (12013’N, 8041’E, 500M above sea level) in the 1999 and 2000 cropping seasons to investigate the influence of cowpea genotypes and sorghum cropping system on cowpea damage by legume pod borer, Maruca testulalis (Fabricius), bean flower thrips, Megalurthrips sjostedti (Trybom) and cowpea aphids, Aphis craccivora Koch. Treatments consisted of a combination of 6 cowpea genotypes, namely, Danila, IT90K-277-2, IT95K-1091-3, IT95K-222- 14, IT96D666 and IT96D-759 and 4 row arrangements, which included 1M:1C, 2M:2C, 1M:2C and 2M:4C rows of millet to rows of cowpea, respectively. The treatments were laid out in split plot design with row arrangement and cowpea genotype as main and sub-treatments, respectively. Maruca damage ratings on cowpea were recorded based on damage to flowers and pod on the peduncles using 1-9 scale. For aphids, level of infestation was assessed by estimating number of aphid colonies on plants/plots at flowering stage using 0-9 scale, while for thrips, infestation was estimated at post-flowering stage using a scale of 1-9. Result showed that all treatments, except Danila and IT96D-759 were less susceptible to pod damage by Maruca in both 1999 and 2000. Maruca pod damage was significantly higher in 2S:4C row arrangement compared to other treatments. Significantly lower aphids and thrips population were recorded on all treatments except Danila and IT6D-759 and Danila and IT95K-1091-3 in both 1999 and 2000, respectively. The mean number of aphids was lower in 1S:1C in 2000 (2.14) and thrips infestation was highest at 2S:4C row arrangement in 1999 and 2000, respectively. The total dry matter and grain yield increased progressively from 1S:1C through 4S:4C in both 1999 and 2000. The present study suggests that sorghum-cowpea inter crop and the use of improved cowpea varieties should be adopted as control measures against the devastating effects of Maruca, aphids and thrips, thereby improving the cowpea dry matter and grain yield.