Cover Crop Effects Increasing Carbon Storage in a Subtropical No‐Till Sandy Acrisol

The long‐term (8‐year) effects of summer (Mucuna spp.) and winter cover crops (Avena strigosa + Vicia sativa and Lolium multiflorum + Vicia sativa) in maize‐based cropping systems on the total, particulate, and mineral‐associated soil carbon (C) stocks in the 0‐ to 0.2‐m layer of a no‐till South Brazilian Acrisol (87 g kg^?1 clay) were evaluated. Annual C sequestration rates and the carbon management index (CMI) were calculated taking a fallow/maize (F/M) system as reference. A greater average C sequestration rate (0.68 Mg ha^?1 yr^?1) and greater C lability (particulate C/mineral‐associated C) were observed in the soil under the Mucuna system, and this was related to the higher biomass input in comparison to the winter cover crop systems. These cropping system effects on amount and lability of soil C were summarized through the CMI. The results highlight the potential of C retention in soils under warm and humid subtropical climate through the adoption of high C input summer cover crops in no‐till production systems aimed at further improvement in soil and environmental quality.     

Effect of a Bangladeshi home-cooking procedure on the amino acid content,trypsin inhibitor activity and in vitro digestibility of some legume seeds

Raw and cooked samples of cultivars ofLens esculenta (Lentils),Pisum sativum (peas),Phaseolus vulgaris (beans),Phaseolus aureus (navy beans)Cicer arietnum (gram), andLathyrus sativus (dhal) as well as precooked commercial products were analysed for amino acids, trypsin inhibitor activity and in vitro protein digestibility. Of the fifteen samples used in the study one lentil sample, one pea sample, two gram samples and one sample of khesari dhal were from Bangladesh, one gram sample was from Sri Lanka. The other samples were obtained either in shops in Norway or from an industrial firm. The latter were also obtained precooked and dried. The two samples obtained in shops were used with hull and dehulled.Neither cooking by a Bangladeshi household procedure nor industrial precooking and drying had any effect on the amino acid contents of the samples.Cooking and precooking reduced the trypsin inhibitor activity of the raw samples more when the original activity was high then when it was low. The inhibitor activity was similar between samples after cooking.Cooking and precooking and drying increased the in vitro protein digestibility in all samples except in the lentils in which the digestibility was reduced.In the raw samples protein digestibility was negatively correlated with the trypsin inhibitor activity.     

Prediction of legume silage digestibility from various laboratory methods

The potential of different laboratory methods to predict legume silage organic matter digestibility (OMD) in vivo was evaluated by using data from thirty‐three pure legume silages in seven experiments. The samples were analysed for crude protein concentration, cell wall composition, in vitro digestibility by the methods of Tilley and Terry [Journal of the British Grassland Society, 18 (1963) , 104–111; OMD_T&T], pepsin‐cellulase solubility (OMS) and gas production (OMD_GAS), and for indigestible neutral‐detergent fibre concentration in situ (INDF). The relationships between the results obtained by the laboratory methods and in vivo OMD, all expressed as ratios, were studied using linear univariate regression models with experiment as a random variable (mixed model). Legume silage digestibility could be estimated with acceptable accuracy by different in vitro methods, but not from the chemical composition of the samples. The highest accuracy in OMD prediction was found with OMS (RMSE 0·0113; R² = 0·965) followed by OMD_GAS (RMSE 0·0149; R² = 0·944), OMD_{T& T} (RMSE 0·0149; R² = 0·940) and INDF (RMSE 0·0168; R² = 0·925). The relationships between the in vitro methods and in vivo digestibility are not universal, and should be determined separately for each laboratory and type of forage. Part of the error in OMD prediction can be attributed to errors in in vivo OMD determination.     

Nutritive value evaluated on rats of new cultivars of common beans (Phaseolus vulgaris) released in Chile

Five new cultivars of common beans (Phaseolus vulgaris) recently released were analyzed for their proximate chemical composition and protein biological quality. The crude protein content in these cultivars ranged from 21.9 percent in cultivar Arroz 3 to 26.9 percent in cultivar Tórtola Diana (dry matter basis). Rats fed cultivar Tórtola INIA gained more weight, had a higher protein intake and registered higher PER and NPR than Tórtola corriente. On the other hand, rats consuming cultivars Arroz 3 and Fleetwood had lower weight gain, lower protein intake and lower PER and NPR than cultivar Coscorrón corriente. However, all these cultivars have a relatively good protein value as compared to other plant protein sources.     

Effect of six-weekly harvests on the yield, chemical composition and dry matter degradability of Panicum maximum and Stylosanthes hamata in Nigeria

The dry matter (DM) yield and degradability of 6‐week‐old harvests of tropical forages were measured over a season. The forages were nitrogen‐fertilized Guinea grass (Panicum maximum, NFG), unfertilized Guinea grass (UFG), Verano stylo (Stylosanthes hamata,VS), a Guinea grass–Verano stylo mixture (GSM) and Guinea grass in the grass–Verano stylo mixture (GGSM). Six‐week‐old forages were made possible through a cutting regime, which produced four harvests in the growing season. The DM yields of the forages differed significantly (P < 0·001) and showed a significant reduction (P < 0·01) across the season. Crude protein and neutral‐detergent fibre concentrations were significantly (P < 0·01) different between the forages but there was no difference between harvests. The DM degradability of the forages at all harvests were significantly (P < 0·001) different with differences in the soluble fraction (a), degradable fraction (b), potential degradability (PD) and effective degradability (ED), but rate of degradability (c) did not show any significant difference between the forages. Significant (P < 0·01) differences were found between harvests for b and PD, and for the interaction between forage and harvest for b, PD and ED but were not found for the a and c fractions. Both the PD and ED values of all the forages fell with advancing harvests. Although the 6‐week‐old harvests of forage were found not to influence the characteristic reduction in yield of tropical grasses over time, it is concluded that such a management system could be used to obtain forage of relatively high nutritive value during the growing season.     

豆科牧草对多花黑麦草化感作用的种间差异

实验室砂培法检测了红三叶、白三叶、杂三叶、黄花草木樨、紫花苜蓿、红豆草和毛苕子等7种豆科牧草茎叶及根的10%水浸提液处理对多花黑麦草种子萌发和幼苗生长的化感作用,结果表明：供试豆科牧草茎叶和根的水浸提液处理对多花黑麦草种子发芽势和幼苗根的生长均有显著（p＜0.05）的化感抑制作用;10%水浸提液处理对多花黑麦草幼叶伸长无显著（p＞0.05）影响,但对幼叶的干物质积累具有抑制作用;豆科牧草对多花黑麦草幼苗生长的化感作用在作用强度和作用机制两方面存在显著的种间差异.     

豆类杂粮作物种子物性参数的试验研究

为了获得豆类杂粮作物相关播种装备的设计依据，选取大豆、绿豆、豌豆、红豆和蚕豆5种典型豆类杂粮作物为研究对象，采用称重法、量筒法、低温烘干法等进行三轴尺寸、千粒重、含水率、密度、休止角、堆积角、摩擦系数、碰撞恢复系数、刚度系数、破碎力、弹性模量和剪切模量等相应物理特性的试验研究。结果表明：所测杂豆种子三轴尺寸的长、宽、高和球度范围分别为4.78～21.11 mm、3.58～15.63 mm、3.61～8.33 mm和0.66～ 0.97；千粒重、含水率和密度范围分别为51.9～1 548.4 g、11.5%～14.4%和1.067～1.323 g·cm^-3；所测杂豆种子休止角和堆积角的范围分别为21.840～35.199°和22.579～33.530°；杂豆种子在PVC板上的静摩擦系数最小，除蚕豆外，其他种子与种子间的静摩擦系数和动摩擦系数均最大。5种杂豆种子中，蚕豆的抗挤压能力最大，绿豆的抗挤压能力最小；豌豆的刚度系数、弹性模量及剪切模量均最大，大豆均最小。杂豆种子物性参数的测量可为杂豆排种器的研发提供理论依据。