Predicting the enhancement carrying capacity of integrated Brachiaria humidicola and Indigofera zollingeriana pasture in coconut plantation

S D Anis, B Bagau and S S Malalantang

Laboratory of Animal Nutrition and Forages Science, Faculty of Animal Science University of Sam Ratulangi. Jln. Kampus UNSRAT 95115, Manado City, Indonesia
Selvie _anis@yahoo.com

Abstract

Brachiaria humidicola is one of tropical grasses well adapted grown under mature coconuts, but crude protein content lower than minimum requirement of ruminant diet. Herbaceous legume integrated as mixed pasture as source of protein failed to persist due to the aggressiveness of this grass. Tree legumes Indigofera zollingeriana, well adapted under shading in coconut plantation, available as an alternative source of protein. This research aimed to study the ability of this tree legume to provide leaves as a source of protein and dry matter which is in turn be able to enhance the carrying capacity of integrated pasture. Tree legume has been planted in different planting spacing (PS) as follows: PS1 = 100 x 100 cm, PS2 = 150 x 150 cm, PS3 = 200 x 200 cm, overlay on Brachiaria humidicola two weeks regrowth pasture after clearing cut. The research shows planting spacing PS2 of Indigofera zollingeriana results good morphological traits and dry weight of forages. Crude protein content of Indigofera zollingerina almost double higher than Brachiaria humidicola. From animal feeds point of view intake and digestibility coefficient o f crude protein of Brachiaria humidicola lower significantly compared Indigofera zollingerina and total digestible nutrients (TDN) as well. Each TDN solely of both forages could provide energy of cattle. In conclution, both forages in mixed pasture could be expected to provide feeds for more body weight of cattle or probably could enhance carrying capacity, but it has to be precisely elucidated in the field through grazing trials.

Keywords: carrying capacity, coconut, humidicola-indigofera, protein

Introduction

Farming systems applied in the eastern part of Indonesia is still an integrated land with industrial plantations include coconut since this commodity is still one of the economic backbone of society, so that it is used for the development of forage crops Anis et al 2015. However, this kind of integration is faced with competition for nutrients, water, and sunlight. Mostly of forage fed to ruminant is derived from local grasses which is low quality contains around 5% of crude protein (CP) lower than ideal protein content on ruminant diet. B. humidicola a kind of tropical grass well adapted under mature coconuts, persist under free-grazing, drought resistant but especially in dry period crude protein content fluctuated and lower than minimum requirement in ruminant diet. Application of synthetic nitrogen fertilizer to increase crude protein content more practice but costly and occurred negative impacts on the environment. Herbaceous legume integrated as mixed pasture failed to persist due to the aggressiveness of this grass. On the other hand, there are some kinds of tree legumes available in Indonesia i.e. I. zollingeriana, highly relished by the ruminant, and well adapted grown underneath mature coconuts Anis et al 2019. This kind of tree legume alternate to replace Leucaena leucocephala which is susceptible to psyllid insect pests has been attack Leucaena. More studies of this Indigofera is widely done in open area full of sun light, while very little information has been reported yet under shade conditions such as underneath mature coconut, in single plant or in mixed pasture. Plant morphology can be measured in plant height, stem diameter, leaf number, branching, and root development. Those variables observed as growth indicator, and to measure the effect of treatment or environmental influences. More over plant growth can be known by the increase in length, stem diameter, plant-covered area, volume or biomass, wet and dry weight of plants Abdullah 2010. This type of legume contains relatively higher crude protein ranging from 22-29% compared to other tree legumes, and fiber content (NDF) is low between 22-46% Abdullah and Suharlina 2010. Along with the increase of human population, competition for the development of extensive forage fodder occurred, because it is used for the development of food agriculture and other infrastructure. Therefore, there needs to be an effort to provide land for growing forage. Since the efficiency of land use in producing nutrition for animals becomes an important issue in a populated region, and evaluation of rows pacing is needed to find an appropriate row spacing for planting Indigofera to produce the highest forage yield and quality. To enhance carrying capacity potential of tropical pasture through integrated tree legume in existing pasture, there is needs to elaborate from animal nutrition aspect studies on dry matter intake, total digestible nutrients (TDN) and predicted the possible augmentation of carrying capacity.

Materials and methods

The experimental was conducted in the experimental station of Assessment Institute of Agricultural Technology (AIAT) of North Sulawesi, located 12 km from Manado City. Experimental site receives an average rainfall of 2700 mm and the distribution fairly even, except for the period of lower rainfall by 100-150 mm monthly, from July to September. The pH of the fertile, sandy loam soil is around 6. Light transmission at 10.00 a.m on a sunny day as PAR underneath mature tall coconuts averaged 73%. The soil has an average pH of 6 and its color was dark brown clay. Precipitation peaks took place in January, with high rainfall intensity. This caused high relative humidity (80%), air temperature ranged from 25⁰ C to 37⁰C.

Table 1 shows that the quality of both forages grown underneath coconuts plantations were varied markedly especially crude protein in I. zollingeriana 27.88% more than double compared to B. humidicola cv Tully by 11.47%. Contrary nitrogen-free extract 45.85% higher than I. zollingeriana 25.39%.

I. zolingeriana seeds obtained from the Agrostology Laboratory of the Faculty of Animal Husbandry, Bogor Agricultural University sown on soil that has been processed as a nursery plots. Seedling that have grown well are then moved into a 15 kg polybag that has already been filled with soil (one plant / bag). After growing for 2 months in a polybag, the plant was then transferred to experimental site in a plot size of 8 x 8 meter that had been processed and divided into 27 subplots to accommodate the 3 treatments for the planting spacing (PS) namely PS1: 1.0 m x 1.0 m, PS2: 1.5 m x 1.5 m, and PS3: 2.0 m x 2.0 m, which was repeated 9 times corresponding to the population of 64 plant, 25 plant and 16 plants respectively, thereby 945 plants population has been used. Each plot of 8 x 8 m was then placed individually in the square planting pattern of coconuts at 10 x 10 meter. I. zollingeriana has been planted overlay B. humidicolapasturetwo weeks regrowth after clearing cut.

Photo 1. Based pasture B. humidicola	Photo 2. B. humidicola - I Zollingeriana

Two groups of variables measured consists of the first group: Morphological traits in term of plant height, stem diameter, leaves number, and number of branches of I. zollingeriana and dry weight of both forages being study. Data I. zollingeriana were calculated each week along 12 weeks consecutive observations has been done before harvesting. Plants that are sampled taken in the middle of the experimental plot in order to avoid border effect. Samples of 500 g of both plants were then dried in an oven at a temperature of 105⁰C for 24 hours to get dry weight. The 3 treatments were arranged in Completely Randomized Design. Data were then statistically analyzed by using analysis of variance (ANOVA) by means of MINITAB (Version 16). Honestly Significance Difference (HSD) was applied to determine the difference among treatments. Differences were considered at p<0.05. The second group: The value of animal nutrition aspect has been done in term of dry matter intake, total digestible nutrients (TDN) and predicted the enhancement of carrying capacity. Forages material used for biological value evaluations the only take from the treatment planting spacing PS2 which have higher yield of both forages. Total digestible collection methods have been used to determine the averages digestible coefficient of dry matter, crude protein, crude fiber, ether extract and nitrogen-free extract. This trial has been done in two periods of time, where 7 days as preliminary periods for adaptation the animals to the new rations and to the stay the animal individually in metabolic cages. The second period of 5 days as feces and intake data collecting. Total feeds on-offered and refused was measured each day during collecting periods, and drinking water for animal was available freely. Do to the limitation of facilities, the present step of this research just only to predict how far the contribution of I.zollingeriana to the enhancement of carrying capacity of pasture-based on B. humidicola grown integrated under different planting spacing of I.zollingeriana, thereby the feeding trial has been done separately between grass and legume leaves. Each forage has been on-offered to the animals in full and restricted feeding, so there were 4 treatments, arranged in 4 x 4 Latin Square Block Design, with the assumption that intake and digestibility are not affected by time and the physiological status of adult livestock (Hazim et al 2018). Eight castrated Onggole- cross breed with average body weight 250 Kg has been used. Data were analyzed statistically with Analysis of Variance Test (ANOVA).

Results

The influence of planting spacing treatments on morphological traits variable measured can be seen in Table 2. Plant height at the age of 12 weeks, the highest (86.57 cm) obtained at the planting spacing1,5 m x 1,5 m (PS2), differ markedly (p< 0.05) higher than planting spacing at 1,0 m x 1,0 (PS1), but there is not significant difference (p > 0.05) compared to planting spacing at 2 x 2 m (PS3).

The highest leaf dry weight production (Table 3) of the I. zollingeriana (14.95% results from the treatment of planting spacing 1.5 m x 1.5 m (PS2) and 15.34 ton ha^-1at planting spacing 2.0 m x 2.0 m (PS3), where both treatments were significantly higher (p<0.05) compared to treatment PS1 12.4 ton ha^-1.

Average digestible coefficient of forages

Table 4 below shows that differences in both forages feed attribute were CP intake of I. zollingeriana163.89 Gr/h/d markedly superior than B. humidicola cv. Tully only 71.88 gr/h/d, followed by apparent digestible coefficient 87.47 and 67.26 (%), and further TDN 66.41 and 62.37 respectively. Nevertheless, both forages solely could provide only the needs of Indonesian cattle with bodyweight around 250 Kg.

Discussions

The increase in plant heights in equidistant spacing (PS2) is probably be due to high rate of stem elongation. Stem elongation is related to the competition to get light between plants in narrow plant spacing that results in a significant taller plant compared to those in wider plant spacing (Widodo et al 2016).The increasing this plant height in PS2 treatment followed by increasing in stem diameter (1.18), where the treatments of PS2 affects the micro environment (temperature, humidity and light) which is facilitate the stem for the nutrients and the development the number of branches (11.60). This founding is in agree with (Kumalasari et al 2017) reported that narrower row spacing reduces the number of branches significantly. It is likely that the greater distance between adjacent plants within rows enhances the abilities of the plants to convert the intercepted solar radiation to leaf production (Telleng et al 2016). The highest number of branches found at treatment PS2 reaching at 11.60 branch. The more number of branches the higher growing point appeared

for leave development and will be related to the availability of energy reserves (carbohydrates) sustain re-growth of forages plant after defoliation or grazing (Craine and Dybzinski 2013); (Anis et al 2016).

The higher dry leaves production is strong related with the high number of branches (Table 2) which is available more growing point for the development of leaves. This phenomenon is probably due to shortage the sun light in coconuts plantation, especially in the very narrow planting spacing (PS1).

Pasture-based on B.humidicola under coconut plantation needs to enriched protein with tree legume, since integrated herbaceous or creeping legume not able to persist in mixed pasture due to aggressiveness growth habit of Brachiaria (Anis et al 2015).

Conclusions

• Planting space at 1.5 x 1.5 meter of I. zollingerianaintegrated with B. humidicola in coconut plantations results good morphological traits and dry weight of both forages.
  
  
• From animal feeds point of view B. humidicola and I. zollingeriana solely could provides dry matter, crude protein and TDN for cattle with bodyweight around 250 Kg.
  
  
• Both forages altogether in mixed pasture could be expected to provide feeds for more body weight of cattle or probably could enhance carrying capacity, but it has to be precisely elucidated in the field through grazing trials.

References

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